Gontier was born in Peterborough, Ontario, Canada on May 25. He was raised in Markham, Ontario. Shortly after his parents divorced, he moved to the Peterborough area, where he initially attended the Adam Scott Collegiate Vocational Institute. In 1995, he moved to the Norwood area, and attended Norwood District High School, where he met and befriended Three Days Grace members Neil Sanderson and Brad Walst.
Outside of Three Days Grace, Gontier has also written and collaborated with numerous writers, musicians and bands. Some of his collaborations include Daughtry, Ian Thornley, Max Martin, Shaun Morgan, Ben Burnley, Art of Dying, Before the Curtain, and fellow musician and long time friends Kevin Brown Grainne Ryan and Kim Brown.
He has also contributed to a number of other albums. He contributed vocals and musical arrangement on "I Don't Care" on Apocalyptica's album, Worlds Collide in 2007.
Gontier was also featured on the track "Raining" by fellow Canadian band Art of Dying on their album Vices and Virtues. His cousin, Cale Gontier, is the bass player for Art of Dying.
In 2006 Gontier was a member of the rock supergroup Big Dirty Band along with Geddy Lee, Alex Lifeson, Jeff Burrows, Ian Thornley and Care Failure, covering "I Fought the Law", as part of the Trailer Park Boys movie soundtrack.
In 2009 Adam Gontier worked with Daughtry on their second studio album Leave This Town. The song, "Back Again", did not make the final cut.
In 2011, Gontier created the record label, Sludge Factory Records, and has signed three acts, one of which is fellow Peterborough band, Before the Curtain.
On January 9, 2013, Gontier resigned from Three Days Grace. He left as the band was about to embark on a co-headlining tour. Matt Walst from My Darkest Days, and brother of bassist Brad Walst, became the new official singer.
As of 2015, Gontier is working with Staind guitarist Mike Mushok on a supergroup called Saint Asonia. The band released their self-titled, debut album on July 31, 2015.
Gontier has won two BMI pop awards as well as Billboard's "Rock Single of the Year". Michael Bell handed him the "Big Time Award", at the 2012 "Wire Awards".
Gontier married Naomi Faith Brewer in 2004. The couple divorced in 2013. He married Jeanie Marie Larsen in March 2015.
In 2005, he went into rehabilitation at the CAMH (Centre for Addiction and Mental Health) in Toronto, where he wrote many of the songs for One-X, including "Never Too Late", which was co-written by Adam's ex-wife, Naomi Faith Brewer. Both Gontier and Brewer wrote the video for the song, and she also appears in the video. While in CAMH in Toronto, Gontier wrote "Pain", "Animal I Have Become", "Get Out Alive", "Over and Over", and "Gone Forever". A docu-drama about his addiction, Behind the Pain, was released in 2007.
Gontier joined singer/songwriter Martin Sexton on the road during his 2012 "Fall Like Rain" tour, providing opening support as a solo artist. He also joined Citizen Cope for a few shows as a solo act.
Gontier continued to do shows and concerts as a solo artist. Several songs have been released, but not as singles, such as "It's All in Your Hands", "Take Me With You", "Too Drunk to Drive" (written by Casey Marshall), "Until the End", "No Regrets", "A Beast in Me (Over and Over It Turns on Me)", and "We Will Never Forget". Gontier had previously performed solo songs like "I Will Stay", "Try to Catch Up With the World", and "Lost Your Shot" in 2011 and 2012.
In early March 2013, Gontier publicly announced and launched his Adam Gontier Solo Live Tour.
On May 11, 2013, Gontier released an official acoustic version and video of the song "Give Me a Reason" from Transit of Venus.Three Days Grace (2003)
Life Starts Now (2009)
Transit of Venus (2012)
with Saint AsoniaSaint Asonia (2015)