To activate your Xfinitymobile.com/activate service, you can follow these steps: Go to the Xfinity Mobile activation page at Enter your Xfinity account information, including your Xfinity ID or email address and password. Follow the prompts to choose your device, select a data plan, and enter your personal and payment information. Once you have completed all the required fields, click on the "Activate Now" button to submit your activation request.