The most lucrative pay-per-view boxer in the history of the game made the announcement in a video posted on Instagram on Saturday.
“I’m coming back in December,” the American said, adding the caption: “I’m coming back to fight Manny Pacquiao this year another 9 figure pay day on the way.”
In the video, Mayweather mocks Pacquiao by asking him about his shoulder, which the Filipino suggested was responsible for his 2015 defeat.
Asked recently about a potential rematch, the Pacman had said: “If he decides to go back to boxing then that is the time we are going to call the shots.
“I have the belt, so it’s up to him. If he wants to come back in boxing, let’s do a second one.”
The duo fought in 2015 with Mayweather coming out on top, and Pacquaio has been after a rematch ever since.
The pound-for-pound boxer retired following his victory over Conor McGregor a year ago but he appears to have been tempted to return.
The first fight was believed to be the most lucrative of all time, worth over £230m to the two fighters.
Amir Khan recently set his sight on fighting Pacquiao although a rematch with Mayweather could be much more attractive to the Filipino.