diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 49a29392da..b214be7fa5 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -1588,6 +1588,17 @@ class When(Expression):
     def set_source_expressions(self, exprs):
         self.condition, self.result = exprs
 
+    def resolve_expression(
+        self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False
+    ):
+        c = super().resolve_expression(query, allow_joins, reuse, summarize, for_save)
+        if for_save and c.condition is not None:
+            # Resolve condition with for_save=False, since it's used as a filter.
+            c.condition = self.condition.resolve_expression(
+                query, allow_joins, reuse, summarize, for_save=False
+            )
+        return c
+
     def get_source_fields(self):
         # We're only interested in the fields of the result expressions.
         return [self.result._output_field_or_none]
diff --git a/docs/releases/5.2.4.txt b/docs/releases/5.2.4.txt
index ebfa556f23..521ed94d6c 100644
--- a/docs/releases/5.2.4.txt
+++ b/docs/releases/5.2.4.txt
@@ -12,3 +12,7 @@ Bugfixes
 * Fixed a regression in Django 5.2.2 where :meth:`HttpRequest.get_preferred_type()
   <django.http.HttpRequest.get_preferred_type>` incorrectly preferred more
   specific media types with a lower quality (:ticket:`36447`).
+
+* Fixed a regression in Django 5.2.3 where ``Value(None, JSONField())`` used in
+  a :class:`~django.db.models.expressions.When` condition was incorrectly
+  serialized as SQL ``NULL`` instead of JSON ``null`` (:ticket:`36453`).
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index 89601de85b..a06fbc6b95 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -29,6 +29,7 @@ from django.db.models import (
     FloatField,
     Func,
     IntegerField,
+    JSONField,
     Max,
     Min,
     Model,
@@ -81,6 +82,7 @@ from .models import (
     Company,
     Employee,
     Experiment,
+    JSONFieldModel,
     Manager,
     Number,
     RemoteEmployee,
@@ -365,6 +367,21 @@ class BasicExpressionsTests(TestCase):
             Number.objects.all(), [None, None], lambda n: n.float, ordered=False
         )
 
+    @skipUnlessDBFeature("supports_json_field")
+    def test_update_jsonfield_case_when_key_is_null(self):
+        obj = JSONFieldModel.objects.create(data={"key": None})
+        updated = JSONFieldModel.objects.update(
+            data=Case(
+                When(
+                    data__key=Value(None, JSONField()),
+                    then=Value({"key": "something"}, JSONField()),
+                ),
+            )
+        )
+        self.assertEqual(updated, 1)
+        obj.refresh_from_db()
+        self.assertEqual(obj.data, {"key": "something"})
+
     def test_filter_with_join(self):
         # F Expressions can also span joins
         Company.objects.update(point_of_contact=F("ceo"))