John Rapson is a composer, pianist, trombonist and recording artist for MoMu Records, Music and Arts, Sound Aspects and Nine Winds whose work mixes ethnic and experimental elements with more conventional jazz forms. Jazz historian Mark Gridley characterizes his music as "extending several trends that were first demonstrated by Charles Mingus and George Russell." He has been professor of music at the University of Iowa since 1993, where he has collaborated on projects with Billy Higgins, Anthony Braxton, Kenny Wheeler, Carla Bley, Steve Swallow, Bennie Wallace, Jack Walrath, Rafael dos Santos, Matt Wilson, Anthony Cox, Mike Lee, Charlie Kohlhase, The Either/Orchestra, David Berkman, Bobby Watson, Rodrigo Ursaia, Jimmy Greene, Dave Pietro, Peter Apfelbaum and Roberto Sion.

Mr. Rapson has written compositions for a variety of configurations and recorded 32 albums, twelve under his own name featuring his original work. In 2017, he premiered a ninety-minute jazz tone poem entitled Hot Tamale Louie that was released as a CD/DVD on Realtime! Records. In 2002, he won first prize in the Julius Hemphill Competition sponsored by the Jazz Composers Alliance for Riff Bass Bridge Head, from the album Daydreams from the Prairie. He was widely reviewed for two albums, Dances and Orations with Anthony Braxton and Water and Blood with Billy Higgins, featuring compositions built from the improvisations of jazz masters. Mystery and Manners, a third project with Brazilian musicians Vinícius Dorin and Nenê Lima, was released in June of 2011 on MoMu Records and in Brazil under the SESC label. In 2013, Rapson released an album of compositions for jazz orchestra entitled The Night Sky and Turquoise Sea and in 2015, Realtime! Records released his score for the soundtrack from Crescendo.

In 1995, Mr. Rapson was commissioned by AT&T to compose Sound Luminesce, a jazz suite that united musicians in Iowa and Japan via fibre optic technology in the first ever trans-pacific "live" performance. Rapson has also taught at Westmont College in Santa Barbara, California (1980-90) and at Wesleyan University in Middletown, Connecticut (1992-93). His concerts and recordings on the west coast include sessions with John Carter, Vinny Golia, Kim Richmond, Bruce Fowler, Clay Jenkins and Alex Cline. His collaborations while in the east included performances or recordings with Julius Hemphill, David Murray, Bill Frisell, Tim Berne, Doc Cheatham, Ed Blackwell, Jay Hoggard, Walter Thompson and Allen Lowe.