diff --git a/news/12005.bugfix.rst b/news/12005.bugfix.rst
new file mode 100644
index 00000000000..98a3e5112df
--- /dev/null
+++ b/news/12005.bugfix.rst
@@ -0,0 +1 @@
+Removed uses of ``datetime.datetime.utcnow`` from non-vendored code.
diff --git a/src/pip/_internal/self_outdated_check.py b/src/pip/_internal/self_outdated_check.py
index 41cc42c5677..eefbc498b3f 100644
--- a/src/pip/_internal/self_outdated_check.py
+++ b/src/pip/_internal/self_outdated_check.py
@@ -28,8 +28,7 @@
 from pip._internal.utils.filesystem import adjacent_tmp_file, check_path_owner, replace
 from pip._internal.utils.misc import ensure_dir
 
-_DATE_FMT = "%Y-%m-%dT%H:%M:%SZ"
-
+_WEEK = datetime.timedelta(days=7)
 
 logger = logging.getLogger(__name__)
 
@@ -73,12 +72,10 @@ def get(self, current_time: datetime.datetime) -> Optional[str]:
         if "pypi_version" not in self._state:
             return None
 
-        seven_days_in_seconds = 7 * 24 * 60 * 60
-
         # Determine if we need to refresh the state
-        last_check = datetime.datetime.strptime(self._state["last_check"], _DATE_FMT)
-        seconds_since_last_check = (current_time - last_check).total_seconds()
-        if seconds_since_last_check > seven_days_in_seconds:
+        last_check = datetime.datetime.fromisoformat(self._state["last_check"])
+        time_since_last_check = current_time - last_check
+        if time_since_last_check > _WEEK:
             return None
 
         return self._state["pypi_version"]
@@ -100,7 +97,7 @@ def set(self, pypi_version: str, current_time: datetime.datetime) -> None:
             # Include the key so it's easy to tell which pip wrote the
             # file.
             "key": self.key,
-            "last_check": current_time.strftime(_DATE_FMT),
+            "last_check": current_time.isoformat(),
             "pypi_version": pypi_version,
         }
 
@@ -229,7 +226,7 @@ def pip_self_version_check(session: PipSession, options: optparse.Values) -> Non
     try:
         upgrade_prompt = _self_version_check_logic(
             state=SelfCheckState(cache_dir=options.cache_dir),
-            current_time=datetime.datetime.utcnow(),
+            current_time=datetime.datetime.now(datetime.timezone.utc),
             local_version=installed_dist.version,
             get_remote_version=functools.partial(
                 _get_current_remote_pip_version, session, options
diff --git a/tests/lib/certs.py b/tests/lib/certs.py
index 54b484ac0e7..9e6542d2d57 100644
--- a/tests/lib/certs.py
+++ b/tests/lib/certs.py
@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from typing import Tuple
 
 from cryptography import x509
@@ -23,8 +23,8 @@ def make_tls_cert(hostname: str) -> Tuple[x509.Certificate, rsa.RSAPrivateKey]:
         .issuer_name(issuer)
         .public_key(key.public_key())
         .serial_number(x509.random_serial_number())
-        .not_valid_before(datetime.utcnow())
-        .not_valid_after(datetime.utcnow() + timedelta(days=10))
+        .not_valid_before(datetime.now(timezone.utc))
+        .not_valid_after(datetime.now(timezone.utc) + timedelta(days=10))
         .add_extension(
             x509.SubjectAlternativeName([x509.DNSName(hostname)]),
             critical=False,
diff --git a/tests/unit/test_self_check_outdated.py b/tests/unit/test_self_check_outdated.py
index c025ff30275..011df08ae14 100644
--- a/tests/unit/test_self_check_outdated.py
+++ b/tests/unit/test_self_check_outdated.py
@@ -49,7 +49,9 @@ def test_pip_self_version_check_calls_underlying_implementation(
     mocked_state.assert_called_once_with(cache_dir=str(tmpdir))
     mocked_function.assert_called_once_with(
         state=mocked_state(cache_dir=str(tmpdir)),
-        current_time=datetime.datetime(1970, 1, 2, 11, 0, 0),
+        current_time=datetime.datetime(
+            1970, 1, 2, 11, 0, 0, tzinfo=datetime.timezone.utc
+        ),
         local_version=ANY,
         get_remote_version=ANY,
     )
@@ -167,7 +169,10 @@ def test_writes_expected_statefile(self, tmpdir: Path) -> None:
 
         # WHEN
         state = self_outdated_check.SelfCheckState(cache_dir=str(cache_dir))
-        state.set("1.0.0", datetime.datetime(2000, 1, 1, 0, 0, 0))
+        state.set(
+            "1.0.0",
+            datetime.datetime(2000, 1, 1, 0, 0, 0, tzinfo=datetime.timezone.utc),
+        )
 
         # THEN
         assert state._statefile_path == os.fspath(expected_path)
@@ -175,6 +180,6 @@ def test_writes_expected_statefile(self, tmpdir: Path) -> None:
         contents = expected_path.read_text()
         assert json.loads(contents) == {
             "key": sys.prefix,
-            "last_check": "2000-01-01T00:00:00Z",
+            "last_check": "2000-01-01T00:00:00+00:00",
             "pypi_version": "1.0.0",
         }