Having secured his future, and with familiar faces in his corner, Reynolds is keen to get started.
"I'm unbelievably happy to be joining Kelly Grove Racing for the 2021 season and beyond," the 35-year-old said.
"It's obviously a very exciting time for the team with the recent investment from the Grove Group.
"I believe the team has the resources and firepower to achieve great things this year and continue building on some of the success we saw last year."
The Kelly operation downscaled to two Ford Mustangs ahead of the 2020 season following a seven-year, four-car Nissan programme.
The retirement of 2006 series champion Kelly marked another key moment for the team, which showed glimpses of performances last season.
Heimgartner, still aged just 25, claimed a maiden pole and two podiums in 2020, to continue his march towards a maiden race win.
With KGR clinching the services of a proven race winner, as well as backing from Penrite, the team heads into 2021 with high expectations.
A pumped Reynolds believes he is armed with what he needs to help KGR take the next step.
"I think we're on the cusp of something really awesome at Kelly Grove Racing, the infrastructure and culture that's in place has already really impressed me and I'm excited for the 2021 season," he said.
"I'm also looking forward to working with Andre as his team-mate, we’ll definitely push each other and hopefully get the two Mustangs up the pointy end.
"It's awesome for me to have a few familiar faces also join the team with Alistair to engineer my side of the garage and obviously Penrite continuing to back my car which is awesome.
"Penrite have been a big supporter of mine over the years, they're family to me so I'm looking forward to continuing that great relationship."
Reynolds will make his competitive KGR debut at the 2021 season opener, the Mt Panorama 500, across February 26-28.