diff --git a/backend/src/db/migrations/20240405000045_org-memberships-unique-constraint.ts b/backend/src/db/migrations/20240405000045_org-memberships-unique-constraint.ts
new file mode 100644
index 000000000..bbe484c7d
--- /dev/null
+++ b/backend/src/db/migrations/20240405000045_org-memberships-unique-constraint.ts
@@ -0,0 +1,15 @@
+import { Knex } from "knex";
+
+import { TableName } from "../schemas";
+
+export async function up(knex: Knex): Promise<void> {
+  await knex.schema.alterTable(TableName.OrgMembership, (table) => {
+    table.unique(["userId", "orgId"]);
+  });
+}
+
+export async function down(knex: Knex): Promise<void> {
+  await knex.schema.alterTable(TableName.OrgMembership, (table) => {
+    table.dropUnique(["userId", "orgId"]);
+  });
+}