Police said they responded to a call from a caretaker at James' home and found him dead, apparently of natural causes.
James became a superstar in 1981 with the release of his triple-platinum album "Street Songs," which included "Super Freak."
He was sentenced to five years in state prison in California in 1994 for assault and drug convictions and was released after two years. He suffered a stroke onstage during a 1998 performance in Denver, and later had hip replacement surgery.
Plans were announced in June in Hollywood for a movie based on James' autobiography, "Memoirs of a Super Freak." He was said to be still writing the book at the time of the announcement.
Comedian Dave Chappelle's new deal with Comedy Central reportedly calls for him to star in the James movie biography for Comedy Central's parent company, Viacom.