He died surrounded by family members at his home in Oceanside, California, his son. Funeral services were held for the singer on Saturday.
Isles learned how to sing as a child in Canton, Ohio. He used the skills he acquired from singing in church to form a music group with childhood friends while they were students at McKinley High School in 1958.
Originally named the Mascots, the group would go on to change its name to the Triumphs and release their first single "Miracles" in 1961. Two years later, the name was changed to the O'Jays after a suggestion from revered Cleveland DJ Eddie O'Jay.
Known for his deep baritone voice, Isles was featured on the popular singles "Lonely Drifter" in 1963 and "Lipstick Traces" in 1965 before quitting the group. Though Isles left center stage, he later played an important role to the O'Jays. According to his son, he worked as a tour manager for the group from 1971 to 1974.
The O'Jays were inducted into the Rock and Roll Hall of Fame in 2005.
After leaving the music industry, Isles founded Nutri Power, a vitamin manufacturing and food supplement company, which he led until the mid-1990s, and did consulting work before retiring around 2000.
His passion for music never stopped. Isles was an active member of the Oceanside New Venture Christian Fellowship choir until his health began to decline in 2018.
Sean Mitchell, founding pastor at New Venture Christian Fellowship, reflected on the singer's legacy: "Billy Isles was exceptional, not only with his voice, but with his buoyancy on stage. He was a lover of music and a lover of God, and he combined both of those on stage in extraordinary fashion.”
Isles is survived by his wife, Laural; sons Duane, Donnell, Billy III and Terry Isles; daughters Denise Isles-Taylor, Rheutitia “Tish” Isles and Laural Gadison; a brother, Ron Isles; sisters Catherine Ann Burt, Johnnie Mae Everett and Octavia Joyce Isles; and seven grandchildren and three great grandchildren, the San Diego Union-Tribune writes.