diff --git a/src/index.ts b/src/index.ts
index fbaf20b..3f89c0c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -197,6 +197,10 @@ export function serialize(
     }
   }
 
+  if (opt.partitioned) {
+    str += "; Partitioned";
+  }
+
   return str;
 }
 
diff --git a/src/types.ts b/src/types.ts
index a6aea2a..7f97f24 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -108,6 +108,17 @@ export interface CookieSerializeOptions {
    * not have an HTTPS connection.
    */
   secure?: boolean | undefined;
+  /**
+   * Specifies the `boolean` value for the [`Partitioned` `Set-Cookie`](rfc-cutler-httpbis-partitioned-cookies)
+   * attribute. When truthy, the `Partitioned` attribute is set, otherwise it is not. By default, the
+   * `Partitioned` attribute is not set.
+   *
+   * **note** This is an attribute that has not yet been fully standardized, and may change in the future.
+   * This also means many clients may ignore this attribute until they understand it.
+   *
+   * More information about can be found in [the proposal](https://github.com/privacycg/CHIPS)
+   */
+  partitioned?: boolean;
 }
 
 /**
diff --git a/test/serialize.test.ts b/test/serialize.test.ts
index 1c82627..5ad32c5 100644
--- a/test/serialize.test.ts
+++ b/test/serialize.test.ts
@@ -261,4 +261,16 @@ describe("serialize(name, value, options)", () => {
       expect(serialize("foo", "bar", { secure: false })).toBe("foo=bar");
     });
   });
+
+  describe('with "partitioned" option', () => {
+    it("should include partitioned flag when true", () => {
+      expect(serialize("foo", "bar", { partitioned: true })).toBe(
+        "foo=bar; Partitioned",
+      );
+    });
+
+    it("should not include partitioned flag when false", () => {
+      expect(serialize("foo", "bar", { partitioned: false })).toBe("foo=bar");
+    });
+  });
 });