diff --git a/backend/src/lib/api-docs/constants.ts b/backend/src/lib/api-docs/constants.ts
index b08c70d93..7d998f8ea 100644
--- a/backend/src/lib/api-docs/constants.ts
+++ b/backend/src/lib/api-docs/constants.ts
@@ -447,7 +447,9 @@ export const PROJECT_USERS = {
   INVITE_MEMBER: {
     projectId: "The ID of the project to invite the member to.",
     emails: "A list of organization member emails to invite to the project.",
-    usernames: "A list of usernames to invite to the project."
+    usernames: "A list of usernames to invite to the project.",
+    roleSlugs:
+      "A list of role slugs to assign to the newly created project membership. If nothing is provided, it will default to the Member role."
   },
   REMOVE_MEMBER: {
     projectId: "The ID of the project to remove the member from.",
diff --git a/backend/src/server/routes/v2/project-membership-router.ts b/backend/src/server/routes/v2/project-membership-router.ts
index 6ab574d64..4aa03f33c 100644
--- a/backend/src/server/routes/v2/project-membership-router.ts
+++ b/backend/src/server/routes/v2/project-membership-router.ts
@@ -26,7 +26,8 @@ export const registerProjectMembershipRouter = async (server: FastifyZodProvider
       }),
       body: z.object({
         emails: z.string().email().array().default([]).describe(PROJECT_USERS.INVITE_MEMBER.emails),
-        usernames: z.string().array().default([]).describe(PROJECT_USERS.INVITE_MEMBER.usernames)
+        usernames: z.string().array().default([]).describe(PROJECT_USERS.INVITE_MEMBER.usernames),
+        roleSlugs: z.string().array().optional().describe(PROJECT_USERS.INVITE_MEMBER.roleSlugs)
       }),
       response: {
         200: z.object({