Andretti will unveil the car and primary sponsor for Busch at a later date.
"I'm really excited to have Kurt come onboard for the Indy 500. He did a great job for us when he tested last year," Andretti said. "He's obviously a natural talent and we feel he is going to take to the Indy car quickly and have a competitive month with us."
Busch, an advocate for The Armed Forces Foundation who is dedicating his effort to the men and women in the U.S. military, will bring at least two personal sponsors.
Cessna has signed on to help with his transportation between IndyCar and NASCAR, and Busch estimates it will require at least 20 hours of flight time shuttling him back and forth between both series. He's also teamed with Basis, a wrist-based health tracker Busch is using to help with his training leading up to the double.
Busch is also taken up martial arts and joked he's entered "a boot camp phase" of his personal training.
"You can get your body ready, and do all the cardio needed and follow the nutritional guidelines," he said. "But the mental aspect of running 1,100 miles is like nothing you can prepare for. I think the martial arts can help with that."
Busch will not participate in an IndyCar race before the Indy 500, but president of competition Derrick Walker said last month the series would try to accommodate him with track time much the same way it has Juan Pablo Montoya in his move from NASCAR back to Indy cars this season.
"To add a driver with the résumé of Kurt Busch to the Indianapolis 500 field is a huge gain for IndyCar," Walker said. "We want to see the best 33 drivers put their skills to the test on the biggest stage in motorsports, regardless of which series they come from. To attempt 'the double' is a tremendous challenge, and we're looking forward to watching Kurt accomplish the feat this May."