As a young man growing up in Kingston, Dillinger would hang around Dennis Alcapone's El Paso sound system. This exposure would eventually lead to work in 1971, as a deejay on the Prince Jackie and El Paso sound systems, initially influenced by Big Youth, U Roy, and Dennis Alcapone, and performing as "Dennis Alcapone Jr.". The first record producer he worked with was Lee "Scratch" Perry, who decided that Bullock should change his name to Dillinger, after gangster John Dillinger. He was part of the second wave of deejay toasters who rose to prominence during the mid-1970s. In 1974, he recorded "Freshly" for Yabby You, and 1975 saw a slew of releases with a variety of producers including Augustus Pablo ("Brace a Boy"), Joseph Hoo Kim ("CB 200"), and Coxsone Dodd ("Killer Man Jaro"). Albums for Dodd (Ready Natty Dreadie) and Hoo Kim (CB 200 and Bionic Dread) would soon follow. His hit "Cocaine In My Brain", which relied heavily on the main tune from "Do It Any Way You Wanna" by the People's Choice was hugely popular internationally, and was a number 1hit in the Netherlands. His output dropped somewhat in the mid-1980s but he returned to recording in the early 1990s. On September 17, 2008, the Mars Volta covered this song during a concert at the Hammerstein Ballroom.
Dillinger was known for his quick wit, humorous lyrics and vulgar content (e.g. on the track "Crabs in My Pants").