Following his debut at the Circuit of the Americas on March 26, he will compete in the inaugural Chicago Street Race on July 2 and the Indianapolis Motor Speedway Road Course on August 13.
The 2009 world champion will be at the wheel of the No. 15 Mobil 1 Ford Mustang of Rick Ware Racing.
"I won the world championship with Mobil 1, and 14 of my 15 wins in Formula One were with Mobil 1, as well as winning the Super GT championship with them," said Button in a statement about as corporate as one can get. "We've had a really close relationship over the years and I can't think of a better partner."
"Obviously, racing a Cup Series car is very different than what I'm used to," he added. "It's a lot heavier with a lot less power and basically no downforce. It's got a sequential gearbox where you need to blip the throttle, so there's lots of stuff to learn in a very short space of time.
"But I just get excited about that new challenge, and when I throw myself into something, I am 100 percent in.
"I'm not just doing it for fun in some one-off," he insisted. "I want to be competitive, and I know that to be competitive, it's going to take a bit of time. That's why doing these three races works very well this season."
Following his retirement from F1 in 2017, Button spent time in the Japanese Super GT Series' GT500 class, winning the 2018 championship, as well as contesting rounds of the World Endurance Championship, including the Le Mans 24 Hours.