diff --git a/neutron_lib/api/definitions/subnet_onboard.py b/neutron_lib/api/definitions/subnet_onboard.py
index f21c779ce..a57feef35 100644
--- a/neutron_lib/api/definitions/subnet_onboard.py
+++ b/neutron_lib/api/definitions/subnet_onboard.py
@@ -41,6 +41,7 @@ ONBOARD_SUBNETS_SPECS = {
 RESOURCE_ATTRIBUTE_MAP = {
     subnetpool_def.COLLECTION_NAME: {
         subnet_def.COLLECTION_NAME: {
+            'allow_post': True, 'allow_put': True,
             'validate': {
                 'type:list_of_any_key_specs_or_none': ONBOARD_SUBNETS_SPECS
             }
diff --git a/releasenotes/notes/subnet-onboard-allow-create-update-subnets-74a4be6e9e97bbb6.yaml b/releasenotes/notes/subnet-onboard-allow-create-update-subnets-74a4be6e9e97bbb6.yaml
new file mode 100644
index 000000000..8712ed5c8
--- /dev/null
+++ b/releasenotes/notes/subnet-onboard-allow-create-update-subnets-74a4be6e9e97bbb6.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - The ``subnet_onboard`` API definition now supports creating and updating
+    subnets