Ali was released from an undisclosed hospital where he received continued treatment for the same condition that initially put him in the hospital late last month, Ali family spokesman Bob Gunnell said.
The former heavyweight champion returned to one of his homes on Friday, the spokesman said.
"He's home and resting and glad to be out of the hospital," Gunnell said.
Ali and his wife, Lonnie, have homes in Paradise Valley, Arizona; Berrien Springs, Michigan; and in Louisville.
Ali turns 73 on Saturday and plans to celebrate with family and friends, Gunnell said. The Louisville native plans to watch television and cheer on the Louisville men's basketball team when the Cardinals play host to Duke on Saturday, he said.
Ali's family said it appreciates an outpouring of support and well wishes.
Ali was hospitalized late last month with what initially was believed to be a mild case of pneumonia. Doctors later determined he was suffering from a urinary tract infection, not pneumonia. That hospital stay lasted more than two weeks.
Ali retired from boxing in 1981 and has focused on social causes since then, travelling the world on humanitarian missions. The Muhammad Ali Center in Louisville is dedicated to Ali's humanitarian causes and showcases his boxing career.
He has waged a long-running fight with Parkinson's disease, and his public appearances have diminished in recent years.
Ali appeared in public in September at a ceremony in his hometown of Louisville for the Muhammad Ali Humanitarian Awards. Ali did not speak to the crowd but posed for photos with award winners, including former NFL great Jim Brown.
Ali received the Presidential Medal of Freedom from President George W. Bush in 2005.