The Amazing Spider-Man star had a surprise role in the Tom Holland film, along with fellow former Spider-Man Tobey Maguire.
While fans had long speculated that the pair would be returning for the movie, Garfield had categorically denied any involvement in the project in public while promoting the Netflix film Tick, Tick… Boom!.
Appearing on the Happy Sad Confused podcast, Garfield was asked if Stone – who played Gwen Stacy opposite his Peter Parker – had seen the film.
“Emma kept on texting me and she was like, ‘Are you in this new Spider-Man film?’” Garfield said.
“I was like, ‘I don’t know what you’re talking about.’ She was like, ‘Shut up, just tell me,’ I’m like, ‘Honestly, don’t know what-’ I kept it going even with her. It was hilarious.”
When Stone finally saw the film, her response was to tell Garfield: “‘You’re a jerk.’”
Garfield and Stone dated from 2010 to 2015, having met on the set of The Amazing Spider-Man.
In a recent interview, Garfield admitted that he’d found lying to the press about the film to be “weirdly enjoyable”.
“It was like this massive game of Werewolf that I was playing with journalists and with people guessing, and it was very fun,” he said.
“There were moments where I was like, ‘God, I hate lying.’ I don’t like to lie and I’m not a good liar, but I kept framing it as a game. And I kept imagining myself purely as a fan of that character, which is not hard to do.”
He continued: “I would want the actor to do an incredibly good job at convincing me he wasn’t in it. And then I would want to lose my mind in the theatre when my instinct was proven right. That’s what I would want.”