Ali "is now at home and looks forward to celebrating his 73rd birthday tomorrow with family & friends," Bob Gunnell said.
The boxing icon, who suffers from Parkinson's disease, was hospitalized Dec. 20 with what was initially believed to be pneumonia.
Doctors later determined that Ali was suffering from a severe urinary tract infection and he was released Jan. 7 from an undisclosed hospital.
The date of his most recent admittance was not revealed.
Ali was the first boxer to win the world heavyweight championship three separate times, successfully defending the title 19 times.
Born Cassius Marcellus Clay Jr., he changed his name to Muhammad Ali in 1964 after converting to Islam.
Known for his exceptional speed, superb footwork, the ability to take a punch and quick wit, he is considered one of the biggest names in world boxing.