Both will drive Triple Eight-built Holden VF Commodores, as they have done this year, which will be run from the team's Banyo workshop.
Triple Eight has raced in the second tier of Supercars three times previously, winning the series in 2011 with Andrew Thompson, finishing runner-up with Scott Pye in 2012, and running Casey Stoner in his single season in cars in 2013.
Next year will represent the first time that it has operated multiple cars in Super2, and comes after its Virgin Australia Supercars Championship efforts were scaled back to two cars with the retirement of Craig Lowndes from full-time racing.
“We as a group really enjoyed running a car in the Development Series a few years ago,” said Team Manager Mark Dutton.
“Roland (Dane, Team Owner) has talked a lot about succession plans for Triple Eight over the last few years and finding the right drivers to continue the team's success is something that's really important, especially since Jamie (Whincup) is now thinking about his own future and when he might hang up the helmet to take on a greater role in running the team.
“It's not only about the drivers as well. We have an opportunity to nurture the young engineers and mechanics and help them make the transition to taking on more responsibility in the main game without completely throwing them in at the deep end.
“On top of all of that, running two cars in Super2 allows us to maintain staff levels, which otherwise would have had to be reduced if only running in the main game with two cars, not three. We've got a fantastic group of people here at Triple Eight and we wanted to do everything we could to keep everyone together.”
As stated by cousin and 2018 team-mate Brodie Kostecki in Newcastle, Kurt Kostecki shifts from the family's Kostecki Brothers Racing operation to Triple Eight, where he worked as a mechanic until midway through this year.
Having previously run evaluation days with the team and been involved in early testing of the ZB Commodore, the 20-year-old is eager to build on a 2018 which was his best Super2 season to date.
Kostecki finished the season eight, as he did in 2017, but picked up maiden podiums along the way.
“I couldn't be more excited for next year,” he said.
“It's a big opportunity for me and I'm looking forward to trying to make the most of it and try to learn off the best team in the business.
“I've already done an evaluation day with Triple Eight and I was very comfortable in that environment because I have known everyone for a few years now after working with the team, so hopefully that translates as soon as we get to Adelaide next year.
“I'm going to take next year as it comes, but we're aiming as high as we can.
“I think there will be no excuses next year for me. I've got the best team to do it behind me, so we're aiming for the top and we'll see what we can do.”
Grove, who is also getting miles in New Zealand's BNT V8s over summer, makes the step after a tough debut year in Super2.
“Triple Eight is obviously the benchmark in Australian motorsport, so to join them and utilise their resources will be awesome. They do things properly, so I'm really excited for next year and seeing what we can achieve.
“I haven't got any major goals, I think it's always good to try and improve when you're out there, so to get towards the top 10 would be nice and that's obviously the objective, but from there, anything can happen, so I'm just going to try to be consistent and keep learning.”
The new season begins on the Superloop Adelaide 500 support card on February 28-March 3.