diff --git a/packages/google-cloud-bigquery/google/cloud/bigquery/_helpers.py b/packages/google-cloud-bigquery/google/cloud/bigquery/_helpers.py
index a35fe1677a8f..fc0b9c959f7b 100644
--- a/packages/google-cloud-bigquery/google/cloud/bigquery/_helpers.py
+++ b/packages/google-cloud-bigquery/google/cloud/bigquery/_helpers.py
@@ -261,7 +261,7 @@ def timestamp_to_py(self, value, field) -> Union[datetime.datetime, str, None]:
             return value
         if _not_null(value, field):
             # value will be a integer in seconds, to microsecond precision, in UTC.
-            return _datetime_from_microseconds(int(value))
+            return _datetime_from_microseconds(int(float(value)))
         return None
 
     def datetime_to_py(self, value, field):