Leitch will join MDK Motorsports in its GTD class Porsche 911 GT3 R alongside Kerong Li and Anders Fjordbach.
Leitch, who is competing in Fanatec GT World Challenge Australia Powered by AWS, will race at the Brickyard on September 20-22.
The Lamborghini Super Trofeo Europe winner last raced at Indianapolis Motor Speedway in 2017 in the Formula 4 United States Championship.
“Last year was massive for me,” said Leitch.
“Winning Lamborghini Super Trofeo Europe with Leipert Motorsport ticked a massive box and since then I’ve been doing absolutely everything I can to make the next step up.”
Leitch is competing in Fanatec GT World Challenge Australia Powered by AWS with countryman Tim Miles.
The pair are third in the drivers’ championship, just three points off the lead.
“I know I’ve proven I’m capable in GT3 cars this year with Melbourne Performance Centre in GT World Challenge Australia beating some of the best Supercars drivers,” said Leitch.
“Anyone who has watched me in Australia this year knows.
“These opportunities to race internationally don’t come around often and I’m keen to make the most of it and turn some heads.
“I’m looking forward to linking up with Kerong again and working with Anders too. I know Kerong has a lot of potential and with Anders I think we can be pushing for a result at the top end.”
It’ll be just the second time Leitch has raced a Porsche 911 GT3 R.
He first cut laps in the rear-engined sports car in GT Open. Leitch was set to race in the Spa 24 with Earl Bamber Motorsport if not for his co-driver crashing in the opening hours of the race.
“The last time I drove a Porsche at Spa-Francorchamps was a bit of a revelation,” said Leitch.
“It’s one of the best GT3 cars and is extremely rewarding as a driver. At a circuit like Indianapolis, I know it’s going to be fantastic.”
Leitch will continue his GT World Challenge Australia season at Phillip Island on August 23-25.