Mayweather, 35, had pleaded guilty to one count of battery-domestic violence and no contest to two counts of harassment in a plea deal that avoided felony charges.
He was sentenced to 87 days in jail and reported to the Clark County Detention Center in Las Vegas June 1. A plea agreement allowed him to miss felony charges, which carried a maximum sentence of 34 years in prison.
He was released Friday when the sentence was reduced because of good behavior.
Mayweather sent a message via Twitter stating, "Thanks for all the support and God Bless everyone who wrote me."
A former girlfriend alleged in September 2010 that Mayweather beat her and threatened her and her children.
Mayweather was given permission to push his original jail report date to June 1, which allowed him to fight Miguel Cotto on May 5, a fight hat guaranteed Mayweather $32 million. Mayweather won the fight on a unanimous decision, improving his professional record to 42-0.