diff --git a/src/taskgraph/run-task/run-task b/src/taskgraph/run-task/run-task
index 34937bec4..672affe8b 100755
--- a/src/taskgraph/run-task/run-task
+++ b/src/taskgraph/run-task/run-task
@@ -1410,6 +1410,59 @@ def main(args):
     if "MOZ_FETCHES" in os.environ:
         fetch_artifacts()
 
+        # If Python is a fetch dependency, add it to the PATH and set
+        # MOZPYTHONHOME to relocate binaries.
+        if "MOZ_PYTHON_HOME" in os.environ:
+            print_line(b"setup", b"Setting up local python environment\n")
+            prev = [os.environ["PATH"]] if "PATH" in os.environ else []
+
+            moz_python_home = os.environ["MOZ_PYTHON_HOME"]
+            if IS_WINDOWS:
+                ext = ".exe"
+                moz_python_bindir = moz_python_home
+            else:
+                ext = ""
+                moz_python_bindir = moz_python_home + "/bin"
+
+            new = os.environ["PATH"] = os.pathsep.join([moz_python_bindir] + prev)
+
+            # Relocate the python binary. The standard way uses PYTHONHOME,
+            # but this conflicts with system python (e.g. used by hg), so the
+            # toolchain python is patched to use MOZPYTHONHOME instead.
+            os.environ["MOZPYTHONHOME"] = moz_python_home
+
+            pyinterp = os.path.join(moz_python_bindir, f"python3{ext}")
+            # just a sanity check
+            if not os.path.exists(pyinterp):
+                raise RuntimeError(
+                    "Inconsistent Python installation: "
+                    "archive found, but no python3 binary "
+                    "detected"
+                )
+
+            if IS_MACOSX:
+                # On OSX, we may not have access to the system certificates,
+                # so use the certifi ones.
+                certifi_cert_file = subprocess.check_output(
+                    [pyinterp, "-c", "import certifi; print(certifi.where())"],
+                    text=True,
+                )
+                os.environ["SSL_CERT_FILE"] = certifi_cert_file.strip()
+                print_line(b"setup", b"patching ssl certificate\n")
+
+            print_line(
+                b"setup", b"updated PATH with python artifact: " + new.encode() + b"\n"
+            )
+
+        if "MOZ_UV_HOME" in os.environ:
+            print_line(b"setup", b"Adding uv to PATH\n")
+            prev = [os.environ["PATH"]] if "PATH" in os.environ else []
+            moz_uv_bindir = os.environ["MOZ_UV_HOME"]
+            new = os.environ["PATH"] = os.pathsep.join([moz_uv_bindir] + prev)
+            print_line(
+                b"setup", b"updated PATH with uv artifact: " + new.encode() + b"\n"
+            )
+
     # Install Python requirements after fetches in case tasks want to use
     # fetches to grab dependencies.
     install_pip_requirements(repositories)