The firm is suing the "Purple Rain" singer in state Supreme Court in Manhattan.
Patterson Belknap Webb & Tyler says in a lawsuit filed Tuesday the musician failed to pay it for handling cases in Ireland, California and New York.
The law firm also says it wasn't paid for representing him in his divorce.
It says he has paid $125,000.
A telephone call to Prince's Paisley Park Enterprises Inc. in Minnesota went unanswered Tuesday night.
The 52-year-old singer is best known for 1980s hits such as "When Doves Cry" and "1999."
His full name is Prince Rogers Nelson.