Tom Brady went "SICKO MODE" at Travis Scott's Coachella set ... grooving to the rapper's popular hits and flashing a Colgate smile for the camera.

The former NFL star hit up the second weekend of the popular SoCal festival ... and, an eagle-eyed fan captured him bouncing around to Scott's performance.

Check out the clip ... Brady's wearing a sweater, hood pulled over his cap -- and, he shoves his hands deep in his pockets, clearly fighting off the cold here.

Despite the chill, TB12's having a great time ... grinning wide while seeming to chat with the people next to him.

It doesn't appear Tom was joined by a romantic partner or anything at the event ... though he's been linked to several big names  -- like Irina Shayk -- since splitting with his ex-wife, Gisele Bündchen.

Brady's been busy in recent weeks with a series of fun events ... including zooming into Pete Carroll's class for a surprise discussion and hitting up David Beckham's birthday party.

He was one of just many celebs who attended Coachella this year ... though it's hard to say there were many more famous attendees than the G.O.A.T..