Just a few minutes after it was announced Tander would depart Triple Eight, Penrite Racing confirmed his appointment.
The five-time Bathurst 1000, including this year alongside Shane van Gisbergen, will be behind the wheel of a Grove Racing Ford Mustang for next year's Sandown 500 and Great Race.
It was also announced that Sebastian Tander, Garth's son, will join the Grove Junior Team competing in the SP Tools Australian Kart Championship.
Tander is the latest major coup for the Braeside operation ahead of next season, with the Groves having signed former Walkinshaw Andretti United engineer Grant McPherson as Technical Director.
Forty-five-year-old, Tander, will also “play a crucial role in mentoring” new recruit Matt Payne in his rookie season.
Grove Racing confirmed in September Payne would make the step up to Supercars' main game alongside David Reynolds.
“I've been fortunate enough to work in some great race teams in Supercars,” said Tander.
“What I have seen Stephen and Brenton Grove achieve in a very short time frame is seriously impressive.”
“When they asked me to be part of what they are building for the future, not only as a driver, but also to help mentor Matt Payne, who has already proven to be an immense talent and also help guide the Grove Junior Team it was something that grabbed my attention.”
Team owner, Stephen Grove added: “We identified the need for an experienced driver to work hand in hand with Matt in his first year.
“Garth was the obvious choice given his proven race-winning pedigree and experience in developing race-winning cars and teams.
“On top of that, we understood the need to bring a calculated driver into the fold to assist with the development of Gen3 in the early stages of the season, as well as the opportunity to take the best possible driving line-up into Bathurst.”
The move to Grove Racing will see Tander drive a Ford for the first time in Supercars after 642 starts and 57 wins in Holden machinery.