Autosport exclusively revealed that Reynolds was firmly in the frame to depart Grove Racing and join Team 18 last month.
That has now been confirmed, Reynolds to join Mark Winterbottom in what will be a highly-experienced line-up at the GM squad next season.
The move comes after Reynolds was only offered a single-year extension at Grove Racing, and opted for the security of what is believed to be a multi-year deal.
He will also be reunited with team manager Bruin Beasley and crew chief Dennis Huisjer, who he worked with at Erebus Motorsport.
“This is just a really exciting time for me," said Reynolds. “I’ve worked with Bruin and Dennis when we won Bathurst [in 2017]. We get along really well and I respect everything they do.
“On top of that I get to race alongside Frosty and people forget that the last season we raced together, Mark and I finished first and third in the championship back in 2015.
“I can’t thank [team owner] Charlie [Schwerkolt] enough. I’ve always admired Charlie and how he conducts himself and his team.
“Funnily enough I’ve always had this feeling that maybe one day I’d race for Charlie, I cannot wait to join him and his team.”
Source: Autosport