diff --git a/remote/webdriver-bidi/modules/root/script.jsm b/remote/webdriver-bidi/modules/root/script.jsm
index 6c0a0ef3002a..39dfe87ed171 100644
--- a/remote/webdriver-bidi/modules/root/script.jsm
+++ b/remote/webdriver-bidi/modules/root/script.jsm
@@ -169,6 +169,52 @@ class ScriptModule extends Module {
     return this.#buildReturnValue(evaluationResult);
   }
 
+  /**
+   * The script.disown command disowns the given handles. This does not
+   * guarantee the handled object will be garbage collected, as there can be
+   * other handles or strong ECMAScript references.
+   *
+   * @param {Object=} options
+   * @param {Array<string>} handles
+   *     Array of handle ids to disown.
+   * @param {Object} target
+   *     The target owning the handles, which either matches the definition for
+   *     a RealmTarget or for ContextTarget.
+   */
+  async disown(options = {}) {
+    // TODO: Bug 1778976. Remove once command is fully supported.
+    this.assertExperimentalCommandsEnabled("script.disown");
+
+    const { handles, target = {} } = options;
+
+    lazy.assert.array(
+      handles,
+      `Expected "handles" to be an array, got ${handles}`
+    );
+    handles.forEach(handle => {
+      lazy.assert.string(
+        handle,
+        `Expected "handles" to be an array of strings, got ${handle}`
+      );
+    });
+
+    const { contextId, realmId, sandbox } = this.#assertTarget(target);
+    const context = this.#getContextFromTarget({ contextId, realmId, sandbox });
+    await this.messageHandler.forwardCommand({
+      moduleName: "script",
+      commandName: "disownHandles",
+      destination: {
+        type: lazy.WindowGlobalMessageHandler.type,
+        id: context.id,
+      },
+      params: {
+        handles,
+        realmId,
+        sandbox,
+      },
+    });
+  }
+
   /**
    * Evaluate a provided expression in the provided target, which is either a
    * realm or a browsing context.
diff --git a/remote/webdriver-bidi/modules/windowglobal/script.jsm b/remote/webdriver-bidi/modules/windowglobal/script.jsm
index 1f41b6512f31..81eb3b471d66 100644
--- a/remote/webdriver-bidi/modules/windowglobal/script.jsm
+++ b/remote/webdriver-bidi/modules/windowglobal/script.jsm
@@ -209,6 +209,8 @@ class ScriptModule extends Module {
    *     The arguments to pass to the function call.
    * @param {string} functionDeclaration
    *     The body of the function to call.
+   * @param {string=} realmId [not supported]
+   *     The id of the realm.
    * @param {OwnershipModel} resultOwnership
    *     The ownership model to use for the results of this evaluation.
    * @param {string=} sandbox
@@ -252,6 +254,26 @@ class ScriptModule extends Module {
     return this.#buildReturnValue(rv, realm, awaitPromise, resultOwnership);
   }
 
+  /**
+   * Delete the provided handles from the realm corresponding to the provided
+   * sandbox name.
+   *
+   * @param {Object=} options
+   * @param {Array<string>} handles
+   *     Array of handle ids to disown.
+   * @param {string=} realmId [not supported]
+   *     The id of the realm.
+   * @param {string=} sandbox
+   *     The name of the sandbox.
+   */
+  disownHandles(options) {
+    const { handles, sandbox: sandboxName = null } = options;
+    const realm = this.#getRealmFromSandboxName(sandboxName);
+    for (const handle of handles) {
+      realm.removeObjectHandle(handle);
+    }
+  }
+
   /**
    * Evaluate a provided expression in the current window global.
    *
@@ -261,6 +283,8 @@ class ScriptModule extends Module {
    *     expression to resolve, if this return value is a Promise.
    * @param {string} expression
    *     The expression to evaluate.
+   * @param {string=} realmId [not supported]
+   *     The id of the realm.
    * @param {OwnershipModel} resultOwnership
    *     The ownership model to use for the results of this evaluation.
    * @param {string=} sandbox