It will be Mayweather's final fight before he serves the remaining 87 days of a 90-day jail sentence meted out after he pleaded guilty to a misdemeanor in a domestic-violence case last December.
Mayweather and Cotto will fight at the MGM Grand Garden Arena in Las Vegas for the junior middleweight championship. In his last bout, Mayweather defeated Victor Ortiz for a piece of the welterweight title in September.
The fight can be seen on HBO Pay-Per-View for $59.95. Three fights are set to precede the main event of Mayweather-Cotto, beginning at 9 p.m. EDT.
Here are the fights on the undercard for Saturday:
Junior middleweight: Saul Canelo Alvarez vs. Shane Mosley
Welterweight: Jessie Vargas vs. Steve Forbes
Junior middleweight: Deandre Latimore vs. Carlos Quintana
Mayweather is undefeated, going 42-0, with 26 knockouts. Cotto is 37-2, with 30 knockouts.
Mayweather is expected to set a record by making at least $32 million on the fight, beating Mike Tyson's previous single-fight record of $30 million in 1997. He is a heavy favorite over Cotto.
Betting Line: Mayweather (-700), Cotto (+450)
Prediction: Cotto will be tough to knock out, but Mayweather should come out on top. Mayweather over Cotto by decision.