diff --git a/graphene/types/datetime.py b/graphene/types/datetime.py
index 7bfd9bd2..d8388f8d 100644
--- a/graphene/types/datetime.py
+++ b/graphene/types/datetime.py
@@ -1,5 +1,7 @@
 import datetime
 
+from dateutil.parser import isoparse
+
 from graphql.error import GraphQLError
 from graphql.language import StringValueNode, print_ast
 
@@ -71,7 +73,7 @@ class DateTime(Scalar):
                 f"DateTime cannot represent non-string value: {repr(value)}"
             )
         try:
-            return datetime.datetime.fromisoformat(value)
+            return isoparse(value)
         except ValueError:
             raise GraphQLError(f"DateTime cannot represent value: {repr(value)}")
 
diff --git a/graphene/types/tests/test_datetime.py b/graphene/types/tests/test_datetime.py
index 12927617..bc992af5 100644
--- a/graphene/types/tests/test_datetime.py
+++ b/graphene/types/tests/test_datetime.py
@@ -227,6 +227,18 @@ def test_time_query_variable(sample_time):
     assert result.data == {"time": isoformat}
 
 
+def test_support_isoformat():
+    isoformat = "2011-11-04T00:05:23Z"
+
+    # test time variable provided as Python time
+    result = schema.execute(
+        """query DateTime($time: DateTime){ datetime(in: $time) }""",
+        variables={"time": isoformat},
+    )
+    assert not result.errors
+    assert result.data == {"datetime": "2011-11-04T00:05:23+00:00"}
+
+
 def test_bad_variables(sample_date, sample_datetime, sample_time):
     def _test_bad_variables(type_, input_):
         result = schema.execute(
diff --git a/setup.py b/setup.py
index 33ceba50..61c99ea4 100644
--- a/setup.py
+++ b/setup.py
@@ -53,7 +53,11 @@ tests_require = [
     "coveralls>=3.3,<5",
 ]
 
-dev_requires = ["ruff==0.5.0"] + tests_require
+dev_requires = [
+    "ruff==0.5.0",
+    "types-python-dateutil>=2.8.1,<3",
+    "mypy>=1.10,<2",
+] + tests_require
 
 setup(
     name="graphene",
@@ -83,6 +87,7 @@ setup(
     install_requires=[
         "graphql-core>=3.1,<3.3",
         "graphql-relay>=3.1,<3.3",
+        "python-dateutil>=2.7.0,<3",
         "typing-extensions>=4.7.1,<5",
     ],
     tests_require=tests_require,
diff --git a/tox.ini b/tox.ini
index 52a7e552..a4a6b37e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,7 +20,7 @@ commands =
 [testenv:mypy]
 basepython = python3.10
 deps =
-    mypy>=1.10,<2
+    .[dev]
 commands =
     mypy graphene