He is best known for his mastery of pyrotechnic effects on the alto – he has said that he “wanted to play on a broader sound basis rather than on chords” (1971 interview with Tam Fiofori)). The opportunity came through his long association with Sun Ra, with whom he performed almost exclusively from 1958 to Ra’s death in 1993, although he did record outside the Arkestra, with Paul Bley’s group in 1964 and Olatunji’s group during the mid-1960s. Critic Scott Yanow has described Allen’s playing as “Johnny Hodges from another dimension”.

Since Sun Ra and John Gilmore died, Allen has led the Arkestra, and has recorded two albums as their bandleader. In May 2004, Allen celebrated his 80th birthday on stage with the Arkestra, as part of their performance at the Ninth Vision Festival in New York City. Allen gave other performances on his birthday in 2008 at Sullivan Hall and at Iridium Jazz Club in 2018, both in New York City.