You can activate your Capital One® Walmart Rewards® Mastercard® online or over the phone. Calling is probably the better option if you're in a hurry because activating your card online requires creating an account first. But both aren't too hard to do and don't take all that much time. And just so you know, you don't have to activate your card immediately, but your account will be cancelled after 3-5 months if you wait too long.

Here's how to activate your Capital One® Walmart Rewards® Mastercard® by phone:

Call Customer Service.
Press “1” for general card inquiries.
Enter your card number, followed by “#.”
Tell the representative your name, phone number and Social Security number.

After the Walmart representative verifies your identity, he or she will be able to activate your account, and you'll be able to use your card immediately.

Here's how to activate your Capital One® Walmart Rewards® Mastercard® online:

Log in or go to Walmart's registration page to create an account.
Click on “Activate My Card.”
Enter your personal information.

Whether you activate your Capital One® Walmart Rewards® Mastercard® online or by phone, make sure to set up an online account (if you haven't already). It will make paying the bill, reviewing recent transactions and otherwise managing your account responsibly way easier. And remember, if you don't activate your Capital One® Walmart Rewards® Mastercard® it will be closed after 3-5 months. Then you'd have to reapply if you want another chance.