Antoine Lussier and Sebastien Chaput formed Ion Dissonance during the late summer of 2001 with the intention of creating a fusion of hardcore and metal that was more complex and daring than what they have done before.

Upon completing their first official line-up, the band released a demo CD named .357, which was quickly put together in 2002 for promotional purposes to various zines, labels and individuals around North America.

With this change, they started playing their first major shows as the opening act for such bands as The Dillinger Escape Plan, Every Time I Die, Daughters, Misery Index, The End, and The Black Dahlia Murder.

During April 2003 they started the recording process for their first LP, Breathing Is Irrelevant with producer Yannick St-Amand (Neuraxis, Martyr, Despised Icon, In Dying Days), the album was completed in June 2003, and it came out in September 2003.

It received many favorable reviews from a number of webzines and magazines including Metal Maniacs, Terrorizer and Unrestrained!.

On Tuesday, June 20, 2006, Gabriel announced his departure from the band, citing personal issues and different interests in music.

"[4] In December 2014, Ion Dissonance announced that Dominic Grimard from the band, The Last Felony will be taking over bass duties for Yannick Desgroseillers due to his health issues.