Police received a telephone call at 12:55 a.m. from Powell, who complained that he was feeling dizzy and was having a hard time breathing, Orange Park Police Chief James H. Boivin said by telephone.
When police and rescue workers arrived, they found Powell in his bedroom with the telephone nearby, Boivin said. Powell did not respond to CPR and was pronounced dead at 1:52 a.m., the chief said.
The cause of death has yet to be determined, but police believe it was heart-related, Boivin said.
"He was supposed to have a meeting with his heart specialist" on Monday, but failed to appear, the chief said. "The doctor said he had heart problems."
Funeral arrangements are pending. Powell is survived by a wife and four children, whose ages were not available, Boivin said.
Lynyrd Skynyrd was one of the major voices of hard-driving, bluesy southern rock 'n' roll in the early 1970s and became a global attraction by 1977 when three band members, including lead singer Ronnie Van Zant, and three others died in a plane crash in Mississippi. Powell was seriously injured.
Lynyrd Skynyrd was inducted the Rock and Roll Hall of Fame in 2006.
Born in 1952, Powell grew up in a traveling military family and went to Bishop Kenny High School in Jacksonville, Fla., where he became friends with Leon Wilkeson, future bassist for Lynyrd Skynyrd.
Powell became a roadie for the band until around 1972 when he helped set up the band's equipment at a school prom. There he sat down at a piano and began to play a version of "Free Bird." Van Zant hired him as keyboardist.
The song featured a keyboard introduction that helped turn the piece into a rock 'n' roll anthem and made Powell a star.
By the band's second album, featuring "Sweet Home Alabama," Lynyrd Skynyrd was a popular fixture. After the death of key members, the band reformed. Powell rejoined the group after a stint performing with a Christian rock band.