|Undefeated Floyd Mayweather wins after a technical knockout|
Mayweather, who came out of retirement for the fight, now has a record of 50-0 - surpassing heavyweight great Rocky Marciano's 49-0 record for most wins without a loss or draw.
McGregor, a mixed martial arts champion who was making his professional boxing debut, failed to pull off what might have been the greatest upset in combat sports history.
But the former apprentice plumber from Dublin made the fight much more compelling than most experts had predicted at the T-Mobile Arena.
McGregor made a brave and spirited start but his 40-year-old opponent dominated from the fourth round.
The end came with a weary McGregor doubled over on the ropes as Mayweather landed two hard left hooks in the 10th.
Speaking after his win, Mayweather said of his opponent: "He's a lot better than I thought he was, he used different angles and was a tough competitor. But I was the better man tonight.
"Our game plan was to take our time, go to him, let him shoot his heavy shots early and then take him out at the end. In the MMA he fights 25 minutes really hard then he starts to slow down."
McGregor said Mayweather was "not that fast or powerful" but was "composed" and "patient with his shots".
"I thought it was close and I thought the stoppage was a little early," he said.
"I get looked at when I'm tired… I was just a little fatigued. It was some buzz, I thought we were close."
The odds at fight time favoured Mayweather by a 5-1 margin.
There were a handful of $1m bets on Mayweather, with three coming in just hours before the fight. The biggest reported bet on McGregor was $100,000.
Some 50 million people were expected to watch the bout in the US alone, with the fight available online or on TV screens to more than one billion homes in 200 different countries.
The fight was predicted to generate up to $600m (£466m), breaking the pay-per-view record set by Mayweather and Manny Pacquiao two years ago.
Whether it will be the richest of all-time is still to be determined, but Mayweather left no doubt of his place in the pantheon of boxing greats.
"This was my last night, tonight I chose the right dance partner to dance with," he said when asked if he would ever be seen in the ring again.