The Jo Bro singer looked totally smitten with the mystery woman as they soaked up the Greek sunshine on the beach -- and judging by their body language, they're definitely past the talking stage.

A shirtless Joe was photographed hugging up on the beach babe, who looked stunning in a blue one-piece bathing suit and a white cap. Definitely not a bad rebound, we must say.

There was even more PDA between them -- JJ and this gal were spotted holding hands ... and the woman showed some playful affection towards Jonas as they got into the water.

Clearly, Joe's moved on pretty fast ... 'cause it was only earlier this month reports emerged of his breakup with Stormi -- whom he was dating for much of this year.

It was a short-lived, whirlwind romance to say the least -- they only started spending time together in early 2024, but they certainly made the most of it, with trips to Los Cabos and Australia.

Joe's romance with Stormi came hot on the heels of his marriage with Sophie Turner ending, which fizzled out last year when he filed for divorce. Of course, that's still playing out.

Things have been anything but sweet for the exes, as they've been locked in a legal battle over custody of their 2 daughters -- even after a brief white flag wave between both parties.