diff --git a/docs/conf.py b/docs/conf.py
index cb605ff6a1..b7fce71c3d 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -32,9 +32,7 @@
 # Replace |version| in the docs with the actual version string.
 rst_epilog = """
 .. |version| replace:: {version}
-""".format(
-    version=version
-)
+""".format(version=version)
 
 # -- General configuration ---------------------------------------------------
 
diff --git a/gapic/cli/generate.py b/gapic/cli/generate.py
index e8eee1f034..e3b0a902ed 100644
--- a/gapic/cli/generate.py
+++ b/gapic/cli/generate.py
@@ -38,7 +38,7 @@
     "--output",
     type=click.File("wb"),
     default=sys.stdout.buffer,
-    help="Where to output the `CodeGeneratorResponse`. " "Defaults to stdout.",
+    help="Where to output the `CodeGeneratorResponse`. Defaults to stdout.",
 )
 def generate(request: typing.BinaryIO, output: typing.BinaryIO) -> None:
     """Generate a full API client description."""
diff --git a/gapic/generator/generator.py b/gapic/generator/generator.py
index f42e40655e..e9e006e748 100644
--- a/gapic/generator/generator.py
+++ b/gapic/generator/generator.py
@@ -131,9 +131,7 @@ def get_response(self, api_schema: api.API, opts: Options) -> CodeGeneratorRespo
             )
 
         # Return the CodeGeneratorResponse output.
-        res = CodeGeneratorResponse(
-            file=[i for i in output_files.values()]
-        )  # type: ignore
+        res = CodeGeneratorResponse(file=[i for i in output_files.values()])  # type: ignore
         res.supported_features |= CodeGeneratorResponse.Feature.FEATURE_PROTO3_OPTIONAL  # type: ignore
         return res
 
diff --git a/gapic/samplegen_utils/snippet_index.py b/gapic/samplegen_utils/snippet_index.py
index 945b43e61f..2a4d752f3b 100644
--- a/gapic/samplegen_utils/snippet_index.py
+++ b/gapic/samplegen_utils/snippet_index.py
@@ -117,7 +117,9 @@ def __init__(self, api_schema: api.API):
         self.metadata_index.client_library.name = (
             api_schema.naming.warehouse_package_name
         )
-        self.metadata_index.client_library.language = snippet_metadata_pb2.Language.PYTHON  # type: ignore
+        self.metadata_index.client_library.language = (
+            snippet_metadata_pb2.Language.PYTHON  # type: ignore
+        )
 
         self.metadata_index.client_library.version = api_schema.gapic_version
 
diff --git a/gapic/samplegen_utils/yaml.py b/gapic/samplegen_utils/yaml.py
index bb558cb269..0d004254be 100644
--- a/gapic/samplegen_utils/yaml.py
+++ b/gapic/samplegen_utils/yaml.py
@@ -116,7 +116,9 @@ def get(self, key, default=None):
         return next(
             iter(
                 [
-                    e.val for e in self.elements if e.key == key  # type: ignore
+                    e.val
+                    for e in self.elements
+                    if e.key == key  # type: ignore
                 ]  # type: ignore
             ),
             default,
diff --git a/gapic/schema/api.py b/gapic/schema/api.py
index b05f6b6dec..4ee478a643 100644
--- a/gapic/schema/api.py
+++ b/gapic/schema/api.py
@@ -941,11 +941,7 @@ def enforce_valid_library_settings(
             selective_gapic_errors = {}
             # TODO(https://github.com/googleapis/gapic-generator-python/issues/2446):
             # Workaround issue in Python 3.14 related to code coverage by adding `# pragma: no branch`
-            for (
-                method_name
-            ) in (
-                library_settings.python_settings.common.selective_gapic_generation.methods
-            ):  # pragma: no branch
+            for method_name in library_settings.python_settings.common.selective_gapic_generation.methods:  # pragma: no branch
                 if method_name not in self.all_methods:
                     selective_gapic_errors[method_name] = "Method does not exist."
                 elif not method_name.startswith(library_settings.version):
@@ -1180,8 +1176,7 @@ def __init__(
                 object.__setattr__(field, "enum", maybe_enum_type)
             else:
                 raise TypeError(
-                    f"Unknown type referenced in "
-                    f"{self.file_descriptor.name}: '{key}'"
+                    f"Unknown type referenced in {self.file_descriptor.name}: '{key}'"
                 )
 
         # Only generate the service if this is a target file to be generated.
diff --git a/gapic/schema/metadata.py b/gapic/schema/metadata.py
index 7df8d0291f..9fc6e43c30 100644
--- a/gapic/schema/metadata.py
+++ b/gapic/schema/metadata.py
@@ -356,7 +356,7 @@ def resolve(self, selector: str) -> str:
             str: An absolute selector.
         """
         if "." not in selector:
-            return f'{".".join(self.package)}.{selector}'
+            return f"{'.'.join(self.package)}.{selector}"
         return selector
 
     def with_context(self, *, collisions: Set[str]) -> "Address":
diff --git a/gapic/schema/naming.py b/gapic/schema/naming.py
index ebf650944f..96b029664f 100644
--- a/gapic/schema/naming.py
+++ b/gapic/schema/naming.py
@@ -86,7 +86,7 @@ def build(
                 "The protos provided do not share a common root package. "
                 "Ensure that all explicitly-specified protos are for a "
                 "single API. "
-                f'The packages we got are: {", ".join(proto_packages)}'
+                f"The packages we got are: {', '.join(proto_packages)}"
             )
 
         # Define the valid regex to split the package.
diff --git a/gapic/schema/wrappers.py b/gapic/schema/wrappers.py
index 17a7832756..f228256742 100644
--- a/gapic/schema/wrappers.py
+++ b/gapic/schema/wrappers.py
@@ -797,7 +797,7 @@ def get_field(
         # Quick check: If this cursor has no message, there is a problem.
         if not cursor.message:
             raise KeyError(
-                f'Field {".".join(field_path)} could not be resolved from '
+                f"Field {'.'.join(field_path)} could not be resolved from "
                 f"{cursor.name}.",
             )
 
diff --git a/gapic/templates/noxfile.py.j2 b/gapic/templates/noxfile.py.j2
index 274ca368e0..3c07c9b6a8 100644
--- a/gapic/templates/noxfile.py.j2
+++ b/gapic/templates/noxfile.py.j2
@@ -12,8 +12,7 @@ import warnings
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 {% if api.naming.module_namespace %}
 LINT_PATHS = ["docs", "{{ api.naming.module_namespace[0] }}", "tests", "noxfile.py", "setup.py"]
@@ -147,12 +146,11 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
+
 
 {% if api.naming.module_namespace %}
     session.run("flake8", "{{ api.naming.module_namespace[0] }}", "tests")
@@ -163,30 +161,37 @@ def lint(session):
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+    
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/noxfile.py b/noxfile.py
index e99bfad597..98d8b44dc8 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -31,10 +31,12 @@
 
 showcase_version = os.environ.get("SHOWCASE_VERSION", "0.35.0")
 ADS_TEMPLATES = path.join(path.dirname(__file__), "gapic", "ads-templates")
-BLACK_VERSION = "black==25.1.0"
-BLACK_PATHS = ["docs", "gapic", "tests", "test_utils", "noxfile.py", "setup.py"]
-# exclude golden files and generated protobuf code
-BLACK_EXCLUDES = "|".join([".*golden.*", ".*pb2.py"])
+RUFF_VERSION = "ruff==0.14.14"
+LINT_PATHS = ["docs", "gapic", "tests", "test_utils", "noxfile.py", "setup.py"]
+# Ruff uses globs for excludes (different from Black's regex)
+# .*golden.* -> *golden*
+# .*pb2.py -> *pb2.py
+RUFF_EXCLUDES = "*golden*,*pb2.py,*pb2.pyi"
 
 ALL_PYTHON = (
     "3.7",
@@ -294,7 +296,7 @@ def showcase_library(
                     }
                 ]
                 update_service_yaml = _add_python_settings(tmp_dir, python_settings)
-                session.run("python", "-c" f"{update_service_yaml}")
+                session.run("python", f"-c{update_service_yaml}")
             # END TODO section to remove.
         if retry_config:
             session.run(
@@ -755,14 +757,19 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
     session.run(
-        "black",
+        "ruff",
+        "format",
         "--check",
-        *BLACK_PATHS,
-        "--extend-exclude",
-        BLACK_EXCLUDES,
+        *LINT_PATHS,
+        "--exclude",
+        RUFF_EXCLUDES,
     )
+
+    # 3. Run Flake8
     session.run(
         "flake8",
         "gapic",
@@ -772,11 +779,54 @@ def lint(session):
 
 @nox.session(python="3.10")
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
+    """Run ruff format.
+
+    DEPRECATED: This session now uses Ruff instead of Black.
+    It formats code style only (indentation, quotes, etc).
+    """
+    session.log(
+        "WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future."
+    )
+
+    session.install(RUFF_VERSION)
+
+    # 1. Format Code (Replaces black)
+    # We do NOT run 'ruff check --select I' here, preserving strict parity.
+    session.run(
+        "ruff",
+        "format",
+        "--line-length=88",  # Standard Black line length
+        *LINT_PATHS,
+        "--exclude",
+        RUFF_EXCLUDES,
+    )
+
+
+@nox.session(python=NEWEST_PYTHON)
+def format(session):
+    """
+    Run ruff to sort imports and format code.
+    """
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
+    session.run(
+        "ruff",
+        "check",
+        "--select",
+        "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
+        *LINT_PATHS,
+    )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
-        *BLACK_PATHS,
-        "--extend-exclude",
-        BLACK_EXCLUDES,
+        "ruff",
+        "format",
+        "--line-length=88",  # Standard Black line length
+        *LINT_PATHS,
     )
diff --git a/tests/integration/goldens/asset/noxfile.py b/tests/integration/goldens/asset/noxfile.py
index 487acba725..1d395a7dfc 100755
--- a/tests/integration/goldens/asset/noxfile.py
+++ b/tests/integration/goldens/asset/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/credentials/noxfile.py b/tests/integration/goldens/credentials/noxfile.py
index af4ba3e285..462cce9248 100755
--- a/tests/integration/goldens/credentials/noxfile.py
+++ b/tests/integration/goldens/credentials/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/eventarc/noxfile.py b/tests/integration/goldens/eventarc/noxfile.py
index c718640903..cd7b4f82fe 100755
--- a/tests/integration/goldens/eventarc/noxfile.py
+++ b/tests/integration/goldens/eventarc/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/logging/noxfile.py b/tests/integration/goldens/logging/noxfile.py
index 8bf90a69f4..e43fa5b2fb 100755
--- a/tests/integration/goldens/logging/noxfile.py
+++ b/tests/integration/goldens/logging/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/logging_internal/noxfile.py b/tests/integration/goldens/logging_internal/noxfile.py
index 8bf90a69f4..e43fa5b2fb 100755
--- a/tests/integration/goldens/logging_internal/noxfile.py
+++ b/tests/integration/goldens/logging_internal/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/redis/noxfile.py b/tests/integration/goldens/redis/noxfile.py
index 4349f5147d..25a3ec57da 100755
--- a/tests/integration/goldens/redis/noxfile.py
+++ b/tests/integration/goldens/redis/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/integration/goldens/redis_selective/noxfile.py b/tests/integration/goldens/redis_selective/noxfile.py
index 4349f5147d..25a3ec57da 100755
--- a/tests/integration/goldens/redis_selective/noxfile.py
+++ b/tests/integration/goldens/redis_selective/noxfile.py
@@ -23,8 +23,7 @@
 
 import nox
 
-BLACK_VERSION = "black[jupyter]==23.7.0"
-ISORT_VERSION = "isort==5.11.0"
+RUFF_VERSION = "ruff==0.14.14"
 
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
@@ -150,42 +149,47 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
-    session.run(
-        "black",
-        "--check",
-        *LINT_PATHS,
-    )
+    session.install("flake8", RUFF_VERSION)
+
+    # 2. Check formatting
+    session.run("ruff", "format", "--check", "--line-length=88", *LINT_PATHS)
 
     session.run("flake8", "google", "tests")
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
-    """Run black. Format code to uniform standard."""
-    session.install(BLACK_VERSION)
-    session.run(
-        "black",
-        *LINT_PATHS,
-    )
+    """(Deprecated) Legacy session. Please use 'nox -s format'."""
+    session.log("WARNING: The 'blacken' session is deprecated and will be removed in the next release. Please use 'nox -s format' in the future.")
+
+    # Just run the ruff formatter (keeping legacy behavior of only formatting, not sorting imports)
+    session.install(RUFF_VERSION)
+    session.run("ruff", "format", "--line-length=88", *LINT_PATHS)
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def format(session):
     """
-    Run isort to sort imports. Then run black
-    to format code to uniform standard.
+    Run ruff to sort imports and format code.
     """
-    session.install(BLACK_VERSION, ISORT_VERSION)
-    # Use the --fss option to sort imports using strict alphabetical order.
-    # See https://pycqa.github.io/isort/docs/configuration/options.html#force-sort-within-sections
+    # 1. Install ruff (skipped automatically if you run with --no-venv)
+    session.install(RUFF_VERSION)
+
+    # 2. Run Ruff to fix imports
+    # check --select I: Enables strict import sorting
+    # --fix: Applies the changes automatically
     session.run(
-        "isort",
-        "--fss",
+        "ruff", "check",
+        "--select", "I",
+        "--fix",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
+
+    # 3. Run Ruff to format code
     session.run(
-        "black",
+        "ruff", "format",
+        "--line-length=88",  # Standard Black line length
         *LINT_PATHS,
     )
 
diff --git a/tests/system/test_lro.py b/tests/system/test_lro.py
index ba7241c2de..c5722ed27d 100644
--- a/tests/system/test_lro.py
+++ b/tests/system/test_lro.py
@@ -37,7 +37,6 @@ def test_lro(echo):
 
     @pytest.mark.asyncio
     async def test_lro_async(async_echo):
-
         future = await async_echo.wait(
             {
                 "end_time": datetime.now(tz=timezone.utc) + timedelta(seconds=1),
diff --git a/tests/unit/common_types.py b/tests/unit/common_types.py
index d8f8375499..4ea17c6429 100644
--- a/tests/unit/common_types.py
+++ b/tests/unit/common_types.py
@@ -94,7 +94,7 @@ def __init__(
         options=False,
         ident=False,
         resource_path=False,
-        meta=None
+        meta=None,
     ):
         self.fields = fields
         self.type = type
diff --git a/tests/unit/generator/test_formatter.py b/tests/unit/generator/test_formatter.py
index 9d613c2b31..5a5e24d68e 100644
--- a/tests/unit/generator/test_formatter.py
+++ b/tests/unit/generator/test_formatter.py
@@ -18,10 +18,9 @@
 
 
 def test_fix_whitespace_top_level():
-    assert (
-        formatter.fix_whitespace(
-            textwrap.dedent(
-                """\
+    assert formatter.fix_whitespace(
+        textwrap.dedent(
+            """\
     import something
 
 
@@ -36,10 +35,9 @@ class TooFarDown:
     class TooClose:  # remains too close
         pass
     """
-            )
         )
-        == textwrap.dedent(
-            """\
+    ) == textwrap.dedent(
+        """\
     import something
 
 
@@ -53,15 +51,13 @@ class TooFarDown:
     class TooClose:  # remains too close
         pass
     """
-        )
     )
 
 
 def test_fix_whitespace_nested():
-    assert (
-        formatter.fix_whitespace(
-            textwrap.dedent(
-                """\
+    assert formatter.fix_whitespace(
+        textwrap.dedent(
+            """\
     class JustAClass:
         def foo(self):
             pass
@@ -70,10 +66,9 @@ def foo(self):
         def too_far_down(self):
             pass
     """
-            )
         )
-        == textwrap.dedent(
-            """\
+    ) == textwrap.dedent(
+        """\
     class JustAClass:
         def foo(self):
             pass
@@ -81,15 +76,13 @@ def foo(self):
         def too_far_down(self):
             pass
     """
-        )
     )
 
 
 def test_fix_whitespace_decorators():
-    assert (
-        formatter.fix_whitespace(
-            textwrap.dedent(
-                """\
+    assert formatter.fix_whitespace(
+        textwrap.dedent(
+            """\
     class JustAClass:
         def foo(self):
             pass
@@ -99,10 +92,9 @@ def foo(self):
         def too_far_down(self):
             return 42
     """
-            )
         )
-        == textwrap.dedent(
-            """\
+    ) == textwrap.dedent(
+        """\
     class JustAClass:
         def foo(self):
             pass
@@ -111,15 +103,13 @@ def foo(self):
         def too_far_down(self):
             return 42
     """
-        )
     )
 
 
 def test_fix_whitespace_intermediate_whitespace():
-    assert (
-        formatter.fix_whitespace(
-            textwrap.dedent(
-                """\
+    assert formatter.fix_whitespace(
+        textwrap.dedent(
+            """\
     class JustAClass:
         def foo(self):
             pass
@@ -130,10 +120,9 @@ def foo(self):
         def too_far_down(self):
             return 42
     """
-            )
         )
-        == textwrap.dedent(
-            """\
+    ) == textwrap.dedent(
+        """\
     class JustAClass:
         def foo(self):
             pass
@@ -142,15 +131,13 @@ def foo(self):
         def too_far_down(self):
             return 42
     """
-        )
     )
 
 
 def test_fix_whitespace_comment():
-    assert (
-        formatter.fix_whitespace(
-            textwrap.dedent(
-                """\
+    assert formatter.fix_whitespace(
+        textwrap.dedent(
+            """\
     def do_something():
         do_first_thing()
 
@@ -158,17 +145,15 @@ def do_something():
         # Something something something.
         do_second_thing()
     """
-            )
         )
-        == textwrap.dedent(
-            """\
+    ) == textwrap.dedent(
+        """\
     def do_something():
         do_first_thing()
 
         # Something something something.
         do_second_thing()
     """
-        )
     )
 
 
diff --git a/tests/unit/generator/test_generator.py b/tests/unit/generator/test_generator.py
index 1e4578b516..9d8545c419 100644
--- a/tests/unit/generator/test_generator.py
+++ b/tests/unit/generator/test_generator.py
@@ -861,13 +861,13 @@ def make_api(
     *protos,
     naming: naming.Naming = None,
     service_yaml_config: service_pb2.Service = None,
-    **kwargs
+    **kwargs,
 ) -> api.API:
     return api.API(
         naming=naming or make_naming(),
         service_yaml_config=service_yaml_config or service_pb2.Service(),
         all_protos={i.name: i for i in protos},
-        **kwargs
+        **kwargs,
     )
 
 
diff --git a/tests/unit/generator/test_options.py b/tests/unit/generator/test_options.py
index 49ae6e216d..8b17aae911 100644
--- a/tests/unit/generator/test_options.py
+++ b/tests/unit/generator/test_options.py
@@ -161,7 +161,7 @@ def test_options_service_yaml_config(fs):
     service_yaml_fpath = "testapi_v2.yaml"
     fs.create_file(
         service_yaml_fpath,
-        contents=("config_version: 3\n" "name: testapi.googleapis.com\n"),
+        contents=("config_version: 3\nname: testapi.googleapis.com\n"),
     )
     opt_string = f"service-yaml={service_yaml_fpath}"
     opts = Options.build(opt_string)
diff --git a/tests/unit/schema/test_api.py b/tests/unit/schema/test_api.py
index 300e8cab89..9d2dab2ec6 100644
--- a/tests/unit/schema/test_api.py
+++ b/tests/unit/schema/test_api.py
@@ -2611,16 +2611,16 @@ def test_mixin_api_methods_locations():
     assert len(ms) == 2
     m1 = ms["ListLocations"]
     m1.options.ClearExtension(annotations_pb2.http)
-    m1.options.Extensions[annotations_pb2.http].selector = (
-        "google.cloud.location.Locations.ListLocations"
-    )
+    m1.options.Extensions[
+        annotations_pb2.http
+    ].selector = "google.cloud.location.Locations.ListLocations"
     m1.options.Extensions[annotations_pb2.http].get = "/v1/{name=examples/*}/*"
     m1.options.Extensions[annotations_pb2.http].body = "*"
     m2 = ms["GetLocation"]
     m2.options.ClearExtension(annotations_pb2.http)
-    m2.options.Extensions[annotations_pb2.http].selector = (
-        "google.cloud.location.Locations.GetLocation"
-    )
+    m2.options.Extensions[
+        annotations_pb2.http
+    ].selector = "google.cloud.location.Locations.GetLocation"
     m2.options.Extensions[annotations_pb2.http].get = "/v1/{name=examples/*}/*"
     m2.options.Extensions[annotations_pb2.http].body = "*"
     api_schema = api.API.build(fd, "google.example.v1", opts=opts)
@@ -3032,9 +3032,9 @@ def get_file_descriptor_proto_for_tests(
     """
 
     field_options = descriptor_pb2.FieldOptions()
-    field_options.Extensions[field_info_pb2.field_info].format = (
-        field_info_pb2.FieldInfo.Format.Value("UUID4")
-    )
+    field_options.Extensions[
+        field_info_pb2.field_info
+    ].format = field_info_pb2.FieldInfo.Format.Value("UUID4")
 
     fd = (
         make_file_pb2(
@@ -4213,9 +4213,9 @@ def test_read_method_settings_from_service_yaml():
     }
     cli_options = Options(service_yaml_config=service_yaml_config)
     field_options = descriptor_pb2.FieldOptions()
-    field_options.Extensions[field_info_pb2.field_info].format = (
-        field_info_pb2.FieldInfo.Format.Value("UUID4")
-    )
+    field_options.Extensions[
+        field_info_pb2.field_info
+    ].format = field_info_pb2.FieldInfo.Format.Value("UUID4")
 
     squid = make_field_pb2(
         name="squid", type="TYPE_STRING", options=field_options, number=1
@@ -4430,9 +4430,9 @@ def test_method_settings_unsupported_auto_populated_field_field_info_format_rais
     the format of the field is `IPV4`.
     """
     field_options = descriptor_pb2.FieldOptions()
-    field_options.Extensions[field_info_pb2.field_info].format = (
-        field_info_pb2.FieldInfo.Format.Value("IPV4")
-    )
+    field_options.Extensions[
+        field_info_pb2.field_info
+    ].format = field_info_pb2.FieldInfo.Format.Value("IPV4")
     squid = make_field_pb2(
         name="squid", type="TYPE_STRING", options=field_options, number=1
     )
@@ -4461,9 +4461,9 @@ def test_method_settings_invalid_multiple_issues():
     # - Not annotated with google.api.field_info.format = UUID4
     # - Not of type string
     # - Required field
-    field_options.Extensions[field_info_pb2.field_info].format = (
-        field_info_pb2.FieldInfo.Format.Value("IPV4")
-    )
+    field_options.Extensions[
+        field_info_pb2.field_info
+    ].format = field_info_pb2.FieldInfo.Format.Value("IPV4")
     squid = make_field_pb2(
         name="squid", type="TYPE_INT32", options=field_options, number=1
     )
diff --git a/tests/unit/schema/wrappers/test_field.py b/tests/unit/schema/wrappers/test_field.py
index dd8367c2ef..69f243ede8 100644
--- a/tests/unit/schema/wrappers/test_field.py
+++ b/tests/unit/schema/wrappers/test_field.py
@@ -143,9 +143,9 @@ def test_not_required():
 
 def test_uuid4():
     field = make_field()
-    field.options.Extensions[field_info_pb2.field_info].format = (
-        field_info_pb2.FieldInfo.Format.Value("UUID4")
-    )
+    field.options.Extensions[
+        field_info_pb2.field_info
+    ].format = field_info_pb2.FieldInfo.Format.Value("UUID4")
     assert field.uuid4
 
 
@@ -186,9 +186,9 @@ def test_ident_sphinx_map():
 
 def test_resource_reference():
     field = make_field(type="TYPE_STRING")
-    field.options.Extensions[resource_pb2.resource_reference].type = (
-        "translate.googleapis.com/Glossary"
-    )
+    field.options.Extensions[
+        resource_pb2.resource_reference
+    ].type = "translate.googleapis.com/Glossary"
 
     assert field.resource_reference == "translate.googleapis.com/Glossary"
 
diff --git a/tests/unit/schema/wrappers/test_method.py b/tests/unit/schema/wrappers/test_method.py
index 088958e06b..87eb959cb8 100644
--- a/tests/unit/schema/wrappers/test_method.py
+++ b/tests/unit/schema/wrappers/test_method.py
@@ -180,7 +180,8 @@ def test_method_paged_result_field_no_page_field():
     method = make_method(
         name="Foo",
         input_message=make_message(
-            name="FooRequest", fields=(make_field(name="page_token", type=9),)  # str
+            name="FooRequest",
+            fields=(make_field(name="page_token", type=9),),  # str
         ),
         output_message=make_message(
             name="FooResponse",