Sam Smith Holdin' On Tight To Boyfriend Brandon Flynn

12/29/2017 8:00 AM PST

Sam Smith and Boyfriend Brandon Flynn Lock Hands in South Florida

EXCLUSIVE

Sam Smith and Brandon Flynn caught some rays Thursday in South Florida ... strolling down the street with unmistakable signs they're a couple.

Sam and the "13 Reasons Why" star grabbed some lunch during the trip to Brandon's family home for the holidays.

They've been together for a few months, but seem to be going strong.  BTW, Brandon's not as young as he plays on the show -- he's 24 and Sam is 25.

Sam's set to start his tour in March ... so it appears they're getting some last minute quality time in.