Flav waited for the perfect moment to dole out the present to the Team USA gymnastics star -- at the VMAs in New York City, while the two were on stage presenting an award.

Flavor Flav turned to Chiles mid-speech and told her, "I know they tried to take your medal away. But you know what? I got you something that they can't take away from you."

He then tied the blinged-out clock around her neck ... while she stood beaming with joy.

"Wow," she said. "I don't even know what to say here."

Minutes later -- after handing off a Moon Person to Taylor Swift and Post Malone for their "Fortnight" collab, Chiles could be seen having a ball with the musicians.

It was all a stark contrast to earlier in the afternoon ... when she had to fight back tears while talking about the bronze that officials stripped from her last month.

On stage at the Forbes Power Women's Summit, she said when the IOC ruled Chiles' Team USA coaches submitted their appeal too late at the Aug. 5 Paris Games floor event and her honor would have to go to Ana Barbosu, she felt like she had lost a part of her.

Clearly, though, Flav helped turn things around.

The cheer-up gift, meanwhile, has been in the making for weeks ... you'll recall, Flav had it created just days after officials had made their ruling -- and he'd just been waiting for the right time to get her it.