Toronto Raptors star Scottie Barnes' Cancun vacation looks like a scene outta "High School Musical" ... 'cause the hooper showed off his awesome singing abilities during a karaoke session!!
The 2021 No. 4 overall pick's offseason started early after the Dino's failed to make the postseason ... but he seemed to be in great spirits nonetheless -- belting out the classic Maroon 5 hit, "This Love."
Barnes put 100% into the performance ... dancing along to the song and doing his best to hit Adam Levine's high notes.