BOXING champion Floyd Mayweather Jr beat mixed martial arts star Conor McGregor via technical knockout in the 10th round, claiming the super welterweight title of the high profile fight on Sunday.

Mayweather came out of retirement at the age of 40, improving his unbeaten record to 50-0.

He became the first boxer to reach 50 fights undefeated, surpassing heavyweight legend Rocky Marciano’s perfect 49-0 record.

During the fight, at the beginning of the first round, southpaw McGregor kept his jabs in Mayweather’s face, teasing his opponent and leaving himself mostly unguarded throughout the round.

Round two saw McGregor getting Mayweather cornered with his series of punches, though several times the former tried to hammer punch and even grapple the latter — leaving him with a warning from the referee.

The UFC champion seemed to occasionally ‘forget’ that he’s fighting under boxing rules and not MMA.

McGregor started going aggressive in rounds three and four, even landing his opponent some solid body shots.

Mayweather looked a bit lost and ‘confused’ with McGregor’s way of attacking.

However, things started to get tiring for McGregor in rounds five and six as his punches seemed more pushed.

The next few rounds saw McGregor doing a lot of shoving, with his punches looking a bit slow and sluggish.

Still, McGregor still seemed like he’s looking for a knockout opportunity.

In round 10, Mayweather charges onto McGregor, showering the latter with damaging strikes.

McGregor survived the attack but his wobbling legs, prompted the referee rush in and to stop the contest, granting Mayweather a technical knockout (TKO) win.

In a post fight interview, Mayweather admitted McGregor was better than he had thought.

He also said that his fight with the Irishman was his last.

"This is my last fight... my last fight," he told the crowd.