Waterbury, Connecticut-born Diorio spent much of the early '60s in Chicago, playing with such stellar jazz musicians as saxophonist Sonny Stitt and trombone player Bennie Green. He made his recording debut on tenor saxophonist Eddie Harris' 1961 album, Exodus to Jazz.

Together with trumpet and saxophone player Ira Sullivan, Diorio relocated to Miami, Florida, where he quickly found a place in the city's thriving jazz scene. In addition to playing with top-notch musicians including Stan Getz, Freddie Hubbard, and Stanley Turrentine, he led his own trio, featuring Bob Magnusson and Jim Plank.

Since releasing his debut solo album, Solo Guitar, in 1975, Diorio has gone on to record more than a dozen impressive platters, including tribute albums to Wes Montgomery and Antonio Carlos Jobim.

Starting with a jazz improvisation class that he taught at the University of Miami, Diorio increasingly turned his focus to teaching. Since relocating to Los Angeles in the late '70s, he has taught in the studio/jazz guitar department of the University of Southern California and the GIT (Guitar Institute of Technology).

He has written several instructional books including Fusion and Intervallic Designs.