Ollie McGill attended Wesley College, Melbourne, Australia. In 1999 McGill on piano was a member of Jazz Cats, a nine-piece jazz group, which issued a four-track extended play, The Jazz Cat. Late that year McGill on keyboards, Ryan Monro on double bass and Felix Riebl on percussion and vocals, founded a split-off group, The Cat Empire.
During 2004 McGill and Harry Angus (also of The Cat Empire) on trumpet and lead vocals, Jules Pascoe on bass guitar, and Harry Shaw-Reynolds on drums formed an improvisational jazz quartet, The Conglomerate. In September 2005 McGill was a founder of a four-piece jazz ensemble, Peaking Duck, with Munro (also in The Cat Empire) on bass guitar, Dave Ades on saxophone and James Hauptmann on drums.
In November 2012 he composed the song, "Dumb Ways to Die", for Metro Trains Melbourne, via agency McCann Melbourne. The song reached the top 10 of the iTunes charts within 24 hours, while the video went viral, achieving over 6 million views in just three days.
McGill also works as a producer, having produced two EPs for ILUKA (Nikki Thorburn), and a number of tracks for Phoebe Eve.
^Jazz Cat (Musical group); Riebl, Felix; Hull-Brown, Will (1999). "The Jazz Cat". Jazz Cat. Retrieved 5 July 2015. Performer: Felix Riebl, percussion; Will Hull-Brown, drums; Ryan Monro, double bass; Ben Edgar, guitar; Ollie McGill, piano; Ross Irwin, trumpet; Eric Budd, trombone; Tarko Sibbel, alto sax; Lachlan McLean, alto and soprano sax.