For background, Apple Pay (AAPL) lets users upload credit and debit card information to a “mobile wallet.” They can then use their iPhone or Apple Watch to pay for goods at retail stores in the U.S. and U.K. that have point-of-sale registers equipped with near field communication technology, known as NFC.

Users can also use their accounts to pay for items within apps, if an app developer has Apple Pay integrated.

Apple had already started accepting users with MasterCard (MC), American Express (AXP), and Visa (V) cards. By turning on the spigot with Discover, Apple is now compatible with all major credit cards.

Apple pay also recently added support for American Express corporate cards, making it easier for corporate expenses to be reimbursed from purchases through Apple Pay.

Discover is trying to entice Apple Pay users to be more active by offering extra 10% cashback bonus on up to $10,000 of in-store purchases. Some Discover cardmembers will also earn an extra 10 airline miles per dollar spent for up to $10,000 of in-store purchases. The offer extends through the end of the year.

Apple hasn’t revealed any numbers on Apple Pay adoption, so it’s tough to know how widespread adoption is. A recent survey by Auriemma Consulting Group showed that 42% of iPhone 6 and iPhone 6 Plus owners have used Apple Pay, and that 70% of Apple Pay users are more likely to choose a store that accepts Apple Pay.

CEO Tim Cook has said that Apple Pay will be accepted by 1.5 million locations in the U.S. by the end of 2015.

For more about Apple Pay, watch this Fortune video: