diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index a710df7b48..043dd4a91b 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -442,6 +442,8 @@ def get_attribute(self, instance):
         except (KeyError, AttributeError) as exc:
             if self.default is not empty:
                 return self.get_default()
+            if self.read_only and self.allow_null:
+                return None
             if not self.required:
                 raise SkipField()
             if self.allow_null:
diff --git a/tests/test_serializer.py b/tests/test_serializer.py
index da1394515c..b00eb0dbd2 100644
--- a/tests/test_serializer.py
+++ b/tests/test_serializer.py
@@ -384,10 +384,16 @@ def create(self, validated_data):
     def test_not_required_output_for_allow_null_field(self):
         class ExampleSerializer(serializers.Serializer):
             omitted = serializers.CharField(required=False, allow_null=True)
+            ommited_read_only = serializers.CharField(
+                required=False,
+                read_only=True,
+                allow_null=True
+            )
             included = serializers.CharField()
 
         serializer = ExampleSerializer({'included': 'abc'})
         assert 'omitted' not in serializer.data
+        assert serializer.data['ommited_read_only'] is None
 
 
 class TestDefaultOutput: