Spencer Pigot will join Ed Carpenter Racing to contest the remaining seven road and street course races on the IndyCar calendar.
The 22-year-old will make his debut with the team at this weekend's double header at Belle Isle, Detroit before taking on Road America, Toronto, Mid-Ohio, Watkins Glen and Sonoma race meetings.
The reigning Indy Lights champion has stepped up to the category this year following his successful 2015 campaign.
“I'm very excited to be joining Ed Carpenter Racing for the remainder of the season on road and street courses,” said Pigot.
“ECR has been very strong in 2016 and I hope we can continue to build on the success they've already had.
“This weekend in Detroit will be the first time we work together, they have a lot of talented people within the team and we will try to hit the ground running.
“I'd also like to thank Bobby Rahal and the RLL team for giving me my first shot in IndyCar.”
Pigot's arrival will see Ed Carpenter Racing field two cars for the remainder of the season alongside its full-time entry for Josef Newgarden.
“We are really excited to be able to add Spencer to the ECR lineup and finish out the year with the (No.) 20 Fuzzy's Vodka car at all of the races,” Carpenter said.
“Spencer is a definite young talent who came through the Road to Indy and we look forward to finishing the year strong with him.”