The rocker, who debuted with the band in 1984 and left and rejoined many times throughout the years, suffered a heart attack at his home in Memphis, Tenn., his booking agent told the Los Angeles Times Monday.
The band released a statement on its Facebook page, saying: "The entire Survivor family is very shocked and saddened by the passing of our brother Jimi Jamison. Our thoughts, love and prayers go out to his family and friends."
One of Survivor's biggest hits, "Eye of the Tiger," was released in 1982—prior to Jamison joining the band. He did, however, co-write and sing Baywatch theme "I'm Always Here," and provided vocals for Survivor's "The Moment of Truth" and "Burning Heart," songs featured in 1984's The Karate Kid and 1985's Rocky IV, respectively.
Other Survivor hits featuring Jamison's vocals include "I Can't Hold Back" and "The Search Is Over."
The band was in in the midst of a reunion tour when Jamison passed away suddenly. Per the BBC, no announcement regarding the remainder of the tour has been made yet.