Karrueche Tran looked ridiculous in Miami Friday ... as in ridiculously hot.

Karrueche was hangin' with a bunch of friends on the beach, and seductive is kind of an understatement.

We broke the story ... she's now dating Quavo from Migos ... we're guessing much to the chagrin of Chris Brown and most other men on planet Earth. We didn't see Migos in Miami, but we know the 2 have been hanging out together in the last month or so, most recently in Biloxi, Mississippi and ATL.

Jealous much?