Adam Carroll will join McLaren's factory GT line-up for the 2013 season.
The 30-year-old from Northern Ireland joins Alexander Sims, Rob Bell and Alvaro Parente in the works McLaren ranks.
Carroll made his sportscar debut with a partial Blancpain Endurance Series and GT1 World Championship programme last year, impressing McLaren GT chief Andrew Kirkaldy.
"I am really pleased that we can add someone with Adam's calibre to our factory driver programme," said Kirkaldy.
"He showed great promise last year in the races he took part in, and he has adapted well to GT racing after a very strong career in single-seaters."
Carroll's first confirmed McLaren drive is in the BES with Gulf Racing UK, sharing with Bell and Nico Verdonck.
Before his sportscar move, Carroll took Ireland to the 2008/09 A1GP title and was a long-time GP2 frontrunner.
He also made two IndyCar starts with AFS/Andretti in 2010 and tested for the BAR/Honda Formula 1 team in the mid-2000s.