Conor celebrated his win at Encore Beach Club, after entering the Octagon Saturday night after a 15-month hiatus. Conor did not disappoint ... a kick to the head in round 1 was all she wrote ... Cerrone went down and Conor pummeled him until the ref stopped the fight.
Fact is ... it's Conor's first victory since 2016, and he needed to win this one -- bad.
The fight -- at the T-Mobile Arena -- was sold out, with more than $11 million in ticket sales alone. Tons of celebs showed up, including Matthew McConaughey, Jeremy Renner, Dave Bautista, Tom Brady, Christian McCaffrey, Baker Mayfield, Myles Garrett and JonGruden.
As for the party ... Conor arrived at 1 AM and stayed until 4 AM.
Get ready ... Conor's promised multiple fights this year.