diff --git a/.generator/cli.py b/.generator/cli.py
index 2d216d0aac3a..417ef2d0a922 100644
--- a/.generator/cli.py
+++ b/.generator/cli.py
@@ -21,6 +21,16 @@
 import subprocess
 from typing import Dict, List
 
+try:
+    import synthtool
+    from synthtool import gcp
+
+    SYNTHTOOL_INSTALLED = True
+    SYNTHTOOL_IMPORT_ERROR = None
+except ImportError as e:
+    SYNTHTOOL_IMPORT_ERROR = e
+    SYNTHTOOL_INSTALLED = False
+
 logger = logging.getLogger()
 
 LIBRARIAN_DIR = "librarian"
@@ -174,6 +184,18 @@ def _locate_and_extract_artifact(bazel_rule: str, library_id: str):
         ) from e
 
 
+def _run_post_processor():
+    """Runs the synthtool post-processor on the output directory.
+    """
+    logger.info("Running Python post-processor...")
+    if SYNTHTOOL_INSTALLED:
+        command = ["python3", "-m", "synthtool.languages.python_mono_repo"]
+        subprocess.run(command, cwd=OUTPUT_DIR, text=True, check=True)
+    else:
+        raise SYNTHTOOL_IMPORT_ERROR
+    logger.info("Python post-processor ran successfully.")
+
+
 def handle_generate():
     """The main coordinator for the code generation process.
 
@@ -185,8 +207,8 @@ def handle_generate():
         ValueError: If the `generate-request.json` file is not found or read.
     """
 
-    # Read a generate-request.json file
     try:
+        # Read a generate-request.json file
         request_data = _read_json_file(f"{LIBRARIAN_DIR}/{GENERATE_REQUEST_FILE}")
         library_id = _get_library_id(request_data)
 
@@ -196,8 +218,8 @@ def handle_generate():
                 bazel_rule = _determine_bazel_rule(api_path)
                 _build_bazel_target(bazel_rule)
                 _locate_and_extract_artifact(bazel_rule, library_id)
+                _run_post_processor()
 
-            logger.info(json.dumps(request_data, indent=2))
     except Exception as e:
         raise ValueError("Generation failed.") from e
 
diff --git a/.generator/test_cli.py b/.generator/test_cli.py
index d14619443a72..552ebaee024e 100644
--- a/.generator/test_cli.py
+++ b/.generator/test_cli.py
@@ -31,6 +31,7 @@
     _read_json_file,
     _run_individual_session,
     _run_nox_sessions,
+    _run_post_processor,
     handle_build,
     handle_configure,
     handle_generate,
@@ -205,6 +206,33 @@ def test_locate_and_extract_artifact_fails(mocker, caplog):
         )
 
 
+def test_run_post_processor_success(mocker, caplog):
+    """
+    Tests that the post-processor helper calls the correct command.
+    """
+    caplog.set_level(logging.INFO)
+    mocker.patch("cli.SYNTHTOOL_INSTALLED", return_value=True)
+    mock_subprocess = mocker.patch("cli.subprocess.run")
+
+    _run_post_processor()
+
+    mock_subprocess.assert_called_once()
+
+    assert mock_subprocess.call_args.kwargs["cwd"] == "output"
+    assert "Python post-processor ran successfully." in caplog.text
+
+
+def test_locate_and_extract_artifact_fails(mocker, caplog):
+    """
+    Tests that an exception is raised if the subprocess command fails.
+    """
+    caplog.set_level(logging.INFO)
+    mocker.patch("cli.SYNTHTOOL_INSTALLED", return_value=True)
+
+    with pytest.raises(FileNotFoundError):
+        _run_post_processor()
+
+
 def test_handle_generate_success(caplog, mock_generate_request_file, mocker):
     """
     Tests the successful execution path of handle_generate.
@@ -215,8 +243,8 @@ def test_handle_generate_success(caplog, mock_generate_request_file, mocker):
         "cli._determine_bazel_rule", return_value="mock-rule"
     )
     mock_build_target = mocker.patch("cli._build_bazel_target")
-
     mock_locate_and_extract_artifact = mocker.patch("cli._locate_and_extract_artifact")
+    mock_run_post_processor = mocker.patch("cli._run_post_processor")
 
     handle_generate()