diff --git a/changelog/20841.txt b/changelog/20841.txt
new file mode 100644
index 000000000000..26a8d6316312
--- /dev/null
+++ b/changelog/20841.txt
@@ -0,0 +1,3 @@
+```release-note:improvement
+openapi: Fix generated types for duration strings
+```
diff --git a/sdk/framework/openapi.go b/sdk/framework/openapi.go
index 53e7ee256c30..663386a179d6 100644
--- a/sdk/framework/openapi.go
+++ b/sdk/framework/openapi.go
@@ -922,8 +922,8 @@ func convertType(t FieldType) schemaType {
 		ret.baseType = "integer"
 		ret.format = "int64"
 	case TypeDurationSecond, TypeSignedDurationSecond:
-		ret.baseType = "integer"
-		ret.format = "seconds"
+		ret.baseType = "string"
+		ret.format = "duration"
 	case TypeBool:
 		ret.baseType = "boolean"
 	case TypeMap: