diff --git a/baseplate/lib/datetime.py b/baseplate/lib/datetime.py
index aaa90c927..71a3e38a7 100644
--- a/baseplate/lib/datetime.py
+++ b/baseplate/lib/datetime.py
@@ -15,6 +15,11 @@ def datetime_to_epoch_seconds(dt: datetime) -> int:
     return datetime_to_epoch_milliseconds(dt) // 1000
 
 
+def epoch_milliseconds_to_datetime(ms: int) -> datetime:
+    """Convert epoch milliseconds to UTC datetime."""
+    return datetime.utcfromtimestamp(ms / 1000).replace(tzinfo=timezone.utc)
+
+
 def epoch_seconds_to_datetime(sec: int) -> datetime:
     """Convert epoch seconds to UTC datetime."""
     return datetime.utcfromtimestamp(sec).replace(tzinfo=timezone.utc)
diff --git a/tests/unit/lib/datetime_tests.py b/tests/unit/lib/datetime_tests.py
index bf75d02ca..db86b4b6a 100644
--- a/tests/unit/lib/datetime_tests.py
+++ b/tests/unit/lib/datetime_tests.py
@@ -7,6 +7,7 @@
 
 from baseplate.lib.datetime import datetime_to_epoch_milliseconds
 from baseplate.lib.datetime import datetime_to_epoch_seconds
+from baseplate.lib.datetime import epoch_milliseconds_to_datetime
 from baseplate.lib.datetime import epoch_seconds_to_datetime
 from baseplate.lib.datetime import get_utc_now
 
@@ -20,6 +21,7 @@ def test_datetime_conversions(self):
         epoch_ms = datetime_to_epoch_milliseconds(EXAMPLE_DATETIME)
         self.assertEqual(EXAMPLE_DATETIME, epoch_seconds_to_datetime(epoch_sec))
         self.assertEqual(epoch_sec, int(epoch_ms / 1000))
+        self.assertEqual(EXAMPLE_DATETIME, epoch_milliseconds_to_datetime(epoch_ms))
 
     def test_timezone_equivalence(self):
         pytz_datetime = EXAMPLE_DATETIME.replace(tzinfo=pytz.UTC)