Andy Fraser, a founder member of Free, died at his Californian home on Monday, according to an official statement.
The Riverside County coroner failed to confirm a cause of death, but Fraser had previously battled cancer and AIDS.
The statement read, "A survivor of both cancer and AIDS, Andy was a strong social activist and defender of individual human rights.
"He leaves behind his daughters Hannah and Jasmine Fraser, and their mother Ri, his sister Gail, brothers Gavin and Alex, and many friends and associates in the industry."
Fraser became a founding member of Free at just 15, and by the time he was 17 All Right Now, which he co-wrote and produced, was a number one hit in more than 20 countries.