The American now has a 50-0 record. And for his efforts, he will pocket about $300m (£230m).
Boxing pundits never expected the fight at T-Mobile arena in Las Vegas, United States, to go the distance, but McGregor lived up to his promise to shock the boxing world.
But in the end Mayweather was just to good.
The end came early in the 10th round. Mayweather attacked again and referee Robert Byrd dived in to save McGregor from any more punishment.
The fight which was delayed because of pay-per-view issues started 5.14 am.
Conor McGregor had control of the first three rounds, doing most of the footwork, with his more experienced opponent Mayweather being overly cautious.
He took control in the 4th round as McGregor appeared to have tired himself out.
In round eight McGregor already looked like a man whose energy had been sapped out of him, and his punches did not cause even a flinch of pain from Mayweather, who appeared to be toying with his opponent at that moment.
Floyd Mayweather has won all 50 of his professional fights, so far.
Conor McGregor has never boxed professionally before today and won 21 of 24 MMA fights.