Tom Boardman is the first driver to sign up for AmD Tuning's first British Touring Car Championship campaign with MG6 cars.
AmD Tuning has taken over the running of the two ex-Triple Eight Racing MGs, which it will field alongside its two Audi S3s.
Boardman, 34, raced in the BTCC's top flight in 2010 and '11 in a family run SEAT Leon. He took an overall victory at Knockhill in 2011.
Since then, he has taken part in World Touring Car Championship races and entered a meeting in the TCR International Series in 2015 in a Ford Focus ST.
Boardman is due to begin his pre-season test programme in the reworked MG shortly.
The Lancastrian driver said: "I'd been looking into the possibility of a programme in TCR this season but when the chance came along to return to the BTCC in the MG, it was one I grabbed with both hands.
"I've always wanted to return to the series but until now, the right deal has never come along.
"I've known the AmD team for a good few years and [team manager] Rob Tickner is someone I have worked with in the past, so I'm confident that I'll fit in well and will be right on the pace when we get to Brands Hatch for the opening rounds."
Team boss Shaun Hollamby said that Boardman's tin-top experience would help AmD's expanded attack for 2018.
"Tom has shown his ability to win races in the past, which isn't an easy feat in this series, and has also shown he has the talent to compete at the highest level from his time in the World Touring Car Championship," said Hollamby.
"To bring a driver with that level of experience on board is great for us as a team."
2018 BTCC line-up so far
WSR BMW: Colin Turkington, Rob Collard, Andrew Jordan
Team Dynamics Honda Civic: Matt Neal, Dan Cammish
Team BMR Subaru Levorg: Ash Sutton, Jason Plato
Speedworks Motorsport Toyota Avensis: Tom Ingram
Eurotech Racing Honda Civic: Jack Goff, Brett Smith, Matt Simpson
Motorbase Performance Ford Focus: Tom Chilton, Sam Tordoff
Power Maxed Racing Vauxhall Astra: Josh Cook, Senna Proctor
Ciceley Racing Mercedes A-Class: Adam Morgan, Tom Oliphant
HMS Racing Alfa Romeo Giulietta: Rob Austin
BTC Norlin Honda Civic: Chris Smiley, James Nash
Laser Tools Racing Mercedes A-Class: Aiden Moffat
Team Hard Volkswagen CC: Jake Hill, Mike Bushell, Michael Caine, Bobby Thompson
AmD Tuning Audi S3: Ollie Jackson, Sam Smelt
AmD Tuning MG: Tom Boardman
Team Parker Racing BMW: Stephen Jelley