MasterCard is moving into the mobile ad business. A year ago, the financial company revamped its established campaign with "Priceless Surprises," a social effort that gave customers spontaneous treats, beginning with a Justin Timberlake appearance. On Wednesday, MasterCard unveiled round two: a new app, built with mobile-ad network Kiip, that lets advertisers reach MasterCard's consumers through smartphone push notifications.

"First, we based it on social media. Now, we're coming into the mobile space," said CMO Raja Rajamannar. The app arrives with a software-development kit, allowing other brands to develop and deliver contextual messages, what Kiip calls "moment-based rewards." MasterCard's partners, like Citibank and Staples, can run co-branded or white-label promotions, Mr. Rajamannar said. "If Apple wants to launch a surprise, they could do it too."

At Mobile World Congress, where the news was announced, Mr. Rajamannar also enthused about Apple Pay, although he declined to comment on specifics. "On a competitive basis, we're in good shape. We're in great shape," he said. The company is also an inaugural partner with Samsung Pay, which is launching this summer. Mr. Rajamannar said Samsung's magnetic-stripe technology would considerably expand mobile-payments. "We're really excited about this one, too," he said.