Pat became intent on a career in music in his early teens, when he became a protégé of jazz education pioneer, Jamey Aebersold. Jamey exposed him to the magic of jazz and instructed Pat in improvisation, arranging, and composition. After graduating from the University of Louisville, where he studied trumpet with Leon Rapier, he spent time free-lancing in New York City and studying with Carmine Caruso. He returned to his native Indiana for graduate study in jazz with David Baker and trumpet with William Adam. Pat's other major teachers include John McNeil and Dominic Spera.

Pat has performed and recorded with his own groups, including his solo debut, After All and the 2002 recording Conspiracy Theory, both on WholeTone Records. In addition to his work as a leader, Pat's credits include work with the Jamey Aebersold Quintet, the PsychoAcoustic Orchestra, The Steve Houghton Quintet, John VonOhlen's Blue Wisp Big Band, and David Baker's 21st Century Bebop Band. In over three decades as a jazz trumpet artist and educator, Pat has performed at major jazz concerts and festivals and taught aspiring musicians about jazz around the world. Pat is the author of many articles on jazz and trumpet, as well as several books, including Technical Studies for the Modern Trumpet and Twenty Authentic Bebop Solos (both published by Aebersold). Harbison also had a long, distinguished career as an educator at the famed Indiana University Jacobs School of Music jazz program.