The 22-year-old steps into the seat alongside team owner Justin McMillan, which had been filled by Reiter Engineering factory pilot Tomas Enge for the opening round in Adelaide.
“I'm so pumped about this opportunity with M-Motorsport,” said Le Brocq.
“The Camaro is an awesome machine and after testing at Phillip Island last week, I can't wait to get racing.
“The cars are still quite new so it's also a chance to help in the development phase, which is something I really enjoy.”
M Motorsport runs two Camaros in the AGTC, with the second shared by car owner Dale Paterson and three-time Bathurst winner Steven Richards.
The team endured a tough run in Adelaide, where electrical problems hampered both cars, which only arrived in Australia in the weeks leading up to the event.
“We're really excited to have Jack on board for the rest of the season,” said McMillan.
“He's had quite a bit of experience in GT cars and has proven he's got the talent.
“Despite some teething problems at the first round, we have every confidence that these cars will be challenging at the front very soon because we know they have the pedigree and speed to be race winners.”
The AGTC continues at Phillip Island on May 22-23, where the series will again run a 101, two-driver, feature race.