Perez was axed by Whitmarsh less than a fortnight ago after just one year at McLaren but Press Association Sport understands the Mexican will drive for Force India next season.
It appears likely Perez will be partnered by Nico Hulkenberg who has reportedly been re-hired by the Silverstone-based team after he quit them a year ago to join Sauber.
Assuming both deals are confirmed, current Force India drivers Paul Di Resta and Adrian Sutil will face an uncertain future in the sport.
In the final race of the season in Brazil, Perez produced a superb drive to finish sixth after starting from 19th.
With driver-movement rumours circulating the Interlagos paddock, the 23-year-old was certainly sporting a grin and far from gave the impression he was leaving the sport.
Whitmarsh, who touted Perez to other teams after letting him go, said: "I am very happy. Lots of stuff has been written, but he's a young man who has been incredibly dignified.
"This is a great job - which can be painful on occasions - but the real hard bit is when you have to make the phone calls and say 'I have decided...', and he took it very well.
"He is very much liked in the team, is a thoroughly likeable guy, and I said to him: 'Prove us wrong'.
"We've done what we can to help him out, and he certainly deserves to be in Formula One, which he proved in this race.
"He is an exciting driver, although at the beginning of the year people were saying he is a bit too exciting.
"But I think you can have that in Formula One - a young man who is prepared to charge, take risks a little and try and fight his way through."
Whitmarsh added: "So I'm delighted for him that we'll see his smiling face in the paddock.
"He is friend of the team now, but we know he'll go out there and try to beat us, and I hope that's the spirit in which he takes it."
Asked if he was saddened about Di Resta's situation, Whitmarsh added: "Of course I am.
"It's a complicated sport these days, and there are drivers with less talent than Paul who will be in the sport - either entering the sport or remaining in the sport - and that's sad.
"It hasn't been announced yet, but it's been fairly well speculated that (his departure) is what is likely to happen."
For McLaren, they at least ended the season on a reasonable high with Jenson Button clinching fourth place, the team's highest position of the campaign.
Although that fourth ensured McLaren avoided the worst year in their history, it is still only the third time since they were formed they have gone through an entire full campaign without a podium.
"I'm happy with the job we did in this race with what we had," said Whitmarsh.
"It was a race where we found the old adrenaline going again because we were racing, it was exciting, and you remember why you flog yourself around the world to do it.
"But it's been a long season - it seemed longer than I've ever known a season - and now I'm excited about the future."