Double Supercars champion Scott McLaughlin will make his IndyCar debut with Penske on the Indianapolis road course.
The DJR Team Penske Supercars driver - who tested for Penske at Sebring last month - will campaign the #2 Team Penske-Chevrolet as reigning IndyCar champion Josef Newgarden takes over the #1 for 2020.
"This is an amazing opportunity - to race against some of the best open wheel drivers in the world on one of the most historic tracks in motorsports," said McLaughlin, who will get a second Indy test at the Circuit of the Americas next week.
"I'm excited about the challenge of trying to win a third-consecutive Supercars championship while helping to keep the Shell V-Power Racing Team at the front of the field this season.
"I'm also really looking forward to this new opportunity.
"It's a driver's dream to get a chance to race an Indy car for Team Penske.
"With the experience I gained at the test in Sebring, I know a little bit more about what to expect when I get back into the car at COTA.
"I just want to learn as much as I can every time I'm in the car so I can make the most of the opportunity to race with the team at the Grand Prix in Indianapolis."
Team owner Roger Penske added: "Scott has experienced tremendous success in Supercars over the last three seasons with DJR Team Penske and we believe his talent and his drive will continue to shine behind the wheel of an Indy car.
"It will be interesting to see how he continues to develop as we work up to his first race at the Indianapolis Grand Prix.
"We know Scott will work hard to improve with every lap and he will represent Team Penske well as he gets acclimated to the IndyCar Series."
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Team Penske has won the last five of the six IndyCar Series races at the Indianapolis Motor Speedway road course since the series began competing at the 2.4-mile track in 2014.
Will Power won the Grand Prix in 2015, 2017 and 2018, while Simon Pagenaud captured the checkered flag in 2016 and again in 2019 for the team.
The GMR Grand Prix at the Indianapolis Motor Speedway takes place on Saturday, May 9.