Born in Baltimore and raised on Division Street, he was the son of Herbert Roy Compton Sr., a Baptist preacher, and Esther Mae Compton, a homemaker. He was a 1956 graduate of Frederick Douglass High School. He then served in the Army.
He went into radio broadcasting and worked at WWRL-AM in New York and WDAS-AM radio in Philadelphia.
Family members said that in 1964, Mr. Compton got a job at WWIN-AM radio in its Waverly studio. He broadcast from 1 a.m. to 6 a.m. and became known as "Sir Johnny O." He remained on the air for 20 years. Friends said he had a smooth, baritone voice and helped train other broadcasters.
He also was the master of ceremonies for a James Brown concert at the old Civic Center and hosted a 1968 Father's Day Revue featuring the Dells, also at the Civic Center.
A 1968 Baltimore Sun article said he led a Sunday night program for teens in the old Crystal Ballroom on North Avenue. About 700 teenagers attended the jacket-and-tie dance, where then-Mayor Thomas J. D'Alesandro III made an appearance.
Mr. Compton also worked at the station at the time of the April 1968 riots that followed the assassination of the Rev. Martin Luther King Jr.
"While he was on the air, someone shot directly at him in the radio station window," said his son, Derrick Gerald Compton Sr. of Baltimore County. "My father was not injured. He remained calm and continued to play music and attempted to keep peace in Baltimore."
He also said his father created the popular "Turnpike Jazz" segment, which aired as part of his all-night show.
During his career, he met artists including Aretha Franklin, Smokey Robinson, Barry White and the Fifth Dimension.
He later worked for WEBB-AM and WITH-AM. He retired about 15 years ago.
Services will be held at 11 a.m. Friday at Good Shepherd Baptist Church, 3459 Park Heights Ave.
In addition to his son, survivors include another son, John Wendell Compton Jr. of Avondale, Ariz.; a daughter, Cheryl Yolanda Compton of Cockeysville; a brother, Herbert Roy Compton Jr. of Owings Mills; two grandchildren; and two great-grandchildren.