Mayweather, 40, started cautiously as UFC lightweight champion McGregor, making his professional boxing debut, landed a first-round uppercut.
But McGregor, 29, looked to tire before the referee called time on the Irishman in Las Vegas.
It saw the former five-weight world champion extend his record to 50-0.
Mayweather said: “He is a tough competitor and we gave the fans what they wanted to see.
“He was a lot better than I thought. He was a tough competitor, but I was the better man.
“I guaranteed everybody this would not go the distance. Boxing’s reputation was on the line.”
Mayweather, who came out of retirement to face McGregor, added: “This was my last fight, for sure. I chose the right dance partner. Conor McGregor, you are a hell of a champion.”
Culled from bbc