Mayweather outclassed McGregor over 10 absorbing rounds at the T-Mobile Arena in Las Vegas.
The 40-year-old American star outclassed McGregor over 10 absorbing rounds at the T-Mobile Arena to defeat Irish mixed martial arts star McGregor by technical knockout.
The win sees Mayweather, who had come out of a two-year retirement to face McGregor, surpass heavyweight legend Rocky Marciano with a perfect record of 50-0.
Afterwards former welterweight king Mayweather insisted he would never be seen in a ring again.
"This was my last fight tonight. For sure," Mayweather said, praising his beaten opponent.
"Tonight was my last fight. Tonight I chose the right dance partner to dance with.
"Conor you are a hell of a champion."
Mayweather also rejected suggestions that his 50th victory -- against an opponent who had never boxed professionally before -- would be destined to have an asterisk against it.
"A win is a win, no matter how you get it," Mayweather said. "Rocky Marciano is a legend and I look forward to going into the Hall of Fame one day."
Mayweather meanwhile revealed the fight had followed a tactical plan as he took his time and allowed McGregor to become fatigued before pouncing in the later rounds.
"Our game plan was to take our time, go to him, let him shoot his shots early and then take him out down the stretch," Mayweather said.
"We know in MMA he fights for 25 minutes. After 25 minutes, he started to slow down. I guaranteed to everybody that this wouldn't go the distance."