Clark County District Attorney David Roger significantly raised the ante in the case alleging that Mayweather hit and threatened the life of his ex-girlfriend, Josie Harris, and threatened to beat two of their children during a pre-dawn argument at the woman's home a week ago.
Mayweather, 33, is one of boxing's most recognizable figures, with a record of 41-0 and 25 knockouts. The welterweight goes by the nickname "Money" and earned more than $20 million in May in one fight in Las Vegas against "Sugar" Shane Mosley
Mayweather remained free on $3,000 bail pending arraignment Nov. 9 following his arrest last Friday on a felony grand larceny charge.
Authorities alleged he took cell phones belonging to Harris and two of their children following the altercation. That felony charge carries a possible sentence of five years.
The new criminal complaint filed Thursday added two felony coercion and one felony robbery charge along with one misdemeanor domestic battery and three misdemeanor harassment charges.
Convictions on all eight charges would increase the possible penalty Mayweather could face if convicted of all charges to 34 years.
Mayweather's lawyer, Richard Wright, told The Associated Press he hadn't seen the new complaint and declined immediate comment.
Wright has previously denied wrongdoing on Mayweather's behalf.
Police initially labeled the scuffle with Harris a domestic battery case after she told police Mayweather was angry about her relationship with another man when he confronted her at the Las Vegas home where Harris and the children live.
Mayweather wanted to evict her from the house, which he owns, Harris said.
The new charges name the couple's 10-year-old son and 9-year-old daughter as victims of coercion, for alleged threats to beat them if they called 911 or left the apartment during the scuffle.
Under Nevada law, coercion is when a person compels or forces someone to do something they have a legal right to do.
The harassment charges allege that Mayweather threatened Harris and the two children, and the battery charge alleges Mayweather grabbed Harris by her hair, hit her and twisted her arm.
The couple had three children, now ages 7 to 10, during what Harris characterized for authorities as a 15-year relationship. She said she lived with Mayweather for seven years before separating in May.
Mayweather also made headlines earlier this month with an online video laced with expletives and racial rants against boxing rival Manny Pacquiao.