The pair will share T8's Pro-Am entry for the Intercontinental GT Challenge with the squad's regular amateur GT driver Prince Jefri Ibrahim.
The car will run under the Boost Mobile Racing and Johor Motorsports Racing banners and will be one of two T8 Mercedes in the race, alongside the all-Pro car for Shane van Gisbergen, Broc Feeney and Maximilian Gotz.
For Stanaway it will be a debut in the Bathurst 12 Hour, although the Kiwi does have extensive GT experience thanks to his time in the World Endurance Championship with Aston Martin.
The race will also mark the beginning of Stanaway's working relationship with T8 following the recent confirmation that he'll team up with Shane van Gisbergen for the Supercars endurance races later this year.
“This year’s Bathurst 12 Hour is going to be a great race to be a part of," said Stanaway.
"I’ve never raced at the 12 Hour before. I did a lot of GT racing when I was in Europe, but it’s been two years now since I’ve driven a GT car.
“I’m looking forward to getting the feeling of a GT car again with its extra downforce compared to what I’ve driven in the past few years. It’s going to really helpful for me to drive at Bathurst again and complete more laps than what I would have done at last year’s Bathurst 1000.
“It’s one of the top international events in the world, and I’m looking forward to experiencing what it’s like. I’m also excited to be sharing a car with Prince Jefri and Jamie – he’s someone I’ve looked up to my whole career.”
Whincup, a Bathurst 12 Hour winner back in 2017, will make his first start in the race since 2020 when he finished third with van Gisbergen and Gotz.
That means this will also be his first start in the round-the-clock enduro since he took over at T8's managing director from Roland Dane.
“The Bathurst 12 Hour is one of the highest-regarded events on the international motorsport calendar – you just have to look at some of the names participating in this year’s race to prove that," he said.
“Teaming up with both Prince Jefri and Richie and having the backing of Boost Mobile and Johor Motorsports Racing is an exciting prospect. Prince Jefri achieved an amazing podium finish at last year’s race, and we all know what Richie is capable of around Mount Panorama.
“To have two Triple Eight-prepared cars participating in this event alongside the world’s best teams is an experience we should all cherish.”
As referenced by Whincup Ibrahim is a Bathurst 12 Hour podium finisher, having teamed up with van Gisbergen and Feeney to finish third in the Pro-Am edition of the race last May.
He and Feeney were then winners at Mount Panorama in November in the three-hour GT race at the Bathurst International.
"Bathurst has always been a special track, and one of my favourites," Ibrahim said.
"There have been a lot of good memories there; from standing on the podium at my first endurance race in 2022 with SVG and Broc, to winning the Bathurst International six months later.
"This year's Bathurst 12 hour will be interesting as there are a lot more cars and international teams entering. Competition will be high, but I'm really looking forward to working alongside Jamie who has a lot of experience, and wins, at this track. It will be my first time driving with Richie, and I'm really excited by our team this year.
"Triple Eight have been working so hard towards this race, and we hope to have a good result, carrying on the positive momentum of last year to fight against the field in 2023."
The 2023 Bathurst 12 Hour will take place on February 3-5.