"I'm proud of him," Jones said in an interview from Sacramento, site of the UFC's weekend televised card. "I think he's listening to his body and he's doing what makes him happy and that's what life is about ultimately.
"He's done a great job and he's been a great example. And he's continuing to be a great example even with the decision that he's made. And I'm happy for him."
Calling his life a "freaking zoo," St-Pierre announced Friday that he was leaving the sport for an undetermined period of time to look after undisclosed personal issues.
The 32-year-old from Montreal leaves the sport ranked No. 2 behind Jones on the UFC's pound-for-pound top fighter list.
Jones, 26, is no stranger to life in the spotlight himself.
He became the UFC's youngest ever champion at 23 when dethroned Mauricio (Shogun) Rua at UFC 128 in March 2011. Away from the cage, he lost his driver's license after crashing his Bentley into a pole in Binghamton, N.Y., in May 2012.
But he said he had no problems with being in the limelight.
"It's great, man. It's great," said Jones, who recently got his license back. "It's a lot of work. There's a lot of perks and I'm grateful for it, man. My story's just getting started."
Jones said he doubted St-Pierre (25-2) would return.
"I don't think he has much more to prove. I think if you go too long on vacation, it just may feel good to have a little gut. He just might stay on vacation."
Light-heavyweight contender Alexander (The Mauler) Gustafsson called GSP's decision to walk away "a little bit sad."
"Because he's the champion and he's a legend in the sport," Gustafsson said in a interview from his native Sweden. "But at the same time, I support him. If he thinks that's the right decision, I understand.
"Only he knows what's best for him."
On Friday, Gustafsson defeated St-Pierre in a fan vote to see who joins Jones on the cover of the upcoming "EA Sports UFC" video game.
Fourteen other fighters were eliminated earlier in the vote.
"I never thought I would make to the cover," said Gustafsson, citing the champions and big names up for the honour.
Jones (19-1) defeated Gustafsson (15-2) in a close fight at UFC 165 in Toronto in September.
The two are expected to fight again in the near future, providing they both win their scheduled bouts in March-April.
No. 1 contender Gustafsson is slated to take on Jimi (Poster Boy) Manuwa on a televised card in March while Jones faces No. 2 Glover Teixeira of Brazil at UFC 172.