Johnson was a former associate of mob boss Stephanie St. Clair. He was one of the leading organized criminals in Harlem to fight an unsuccessful war against Dutch Schultz, who incorporated the city's organized crime into the Jewish and Italian mobs of the day. He was later hired as an enforcer by the Genovese crime family to protect Mafia operations in Black neighborhoods against local Harlem criminals.

Johnson was arrested more than 40 times and would eventually serve three prison terms for narcotics-related charges before dying of a heart attack in 1968 at Harlem's Wells Restaurant. Frank Lucas claimed to be with Bumpy at his death, but Johnson's widow disputes this account and claims Lucas has exaggerated his relationship with Johnson. Lucas claims to have been mentored by Bumpy as his driver and enforcer of 15 years. [1] At the time of his death, Johnson's case was pending for another narcotics violation that could have earned him a possible fourth prison term.

While in prison Johnson studied philosophy and history. Johnson also wrote poetry, some of which was published during the Harlem Renaissance.[citation needed]

Once in December 1965, Johnson staged a sit-down strike in a police station, refusing to leave, as a protest against their continued surveillance. He was charged with "refusal to leave a police station" but was acquitted by a judge.