diff --git a/nova/conf/flavors.py b/nova/conf/flavors.py
index d79f09e44944..e6d66c08c400 100644
--- a/nova/conf/flavors.py
+++ b/nova/conf/flavors.py
@@ -19,8 +19,10 @@ from oslo_config import cfg
 flavor_opts = [
     cfg.StrOpt('default_flavor',
                default='m1.small',
-               help='Default flavor to use for the EC2 API only. The Nova API '
-               'does not support a default flavor.'),
+               deprecated_for_removal=True,
+               deprecated_reason='The EC2 API is deprecated',
+               help='DEPRECATED: Default flavor to use for the EC2 API only. '
+                    'The Nova API does not support a default flavor.'),
 ]
 
 
diff --git a/releasenotes/notes/deprecate-default-flavor-6c144f67f8032dfa.yaml b/releasenotes/notes/deprecate-default-flavor-6c144f67f8032dfa.yaml
new file mode 100644
index 000000000000..f23e0889b6cc
--- /dev/null
+++ b/releasenotes/notes/deprecate-default-flavor-6c144f67f8032dfa.yaml
@@ -0,0 +1,5 @@
+---
+deprecations:
+  - The ``default_flavor`` config option is now deprecated and may be removed
+    as early as the 15.0.0 release. It is an option which was only relevant
+    for the deprecated EC2 API and is not used in the Nova API.