His first
Broadway performance was in 1999, playing
Gavroche in the musical
Les Misérables. He played the role for a year and a half before leaving to do
A Christmas Carol at
Madison Square Garden in 2000 & 2001, playing the role of Jonathan. In 2001, Canonico joined the national tour of
Casper the Musical, performing alongside
Chita Rivera, in Pittsburgh, Kansas City, Atlanta, and Dallas. In 2002, Canonico portrayed Louis in
The King and I at the
Paper Mill Playhouse. While he was still performing in
Les Misérables he participated in readings for the
off-Broadway musical
The Prince and the Pauper at the Lamb's Theatre. He played the Pauper Tom Canty at the show's opening and for several months until he was thought to have grown out of the role. In 2004, Canonico played Brett in the off-Broadway musical ''Children's Letters to God'', also at the Lamb's Theatre. Canonico performed as an ensemble member and as an understudy for all male roles (excluding Melchior Gabor) in the
Broadway musical
Spring Awakening, which opened on November 10, 2006, at the
Eugene O'Neill Theatre. He took over the role of Moritz from August 4, 2008, until the show closed on January 18, 2009. In the summer of 2009 Gerard was involved in
American Idiot, a musical based on the hit
Green Day album, along with fellow
Spring Awakening cast members Brian Charles Johnson and
John Gallagher, Jr. American Idiot premiered in
Berkeley, California on September 4, 2009. Gerard stayed with the show until its April 24, 2011 closing as a member of the ensemble while also understudying two other featured ensemble tracks. Canonico appeared as Goliath in the Off-Broadway production of "Stand Tall", a musical based on the story of David and Goliath. This was presented as part of the NYMF Festival during the summer of 2012. He appeared as the principal role of Matt in the rock musical
Bare at the New World Stages in NY. The play concerns a group of teens wrestling with their identities, sexuality, and religion at a co-ed Catholic boarding school and navigating the complex road from adolescence to adulthood. His character has the problem of always being second best compared to the school's golden-boy, Jason. His girlfriend, Ivy, breaks up with him for Jason. Previews began on November 19, 2012, and the show officially opened on December 9, 2012. It ran through February 3, 2013. Canonico also appeared in a 15-minute musical called
21 Chump Street, written by
Lin-Manuel Miranda on June 7, 2014. Canonico appeared in the world premiere of the Off-Broadway show
Brooklynite (reuniting with Spring Awakening director Michael Mayer as well as former castmates Matt Doyle and Remy Zaken) at the
Vineyard Theatre. The show ran from January 30 to March 22, 2015. Canonico performed the role of Rich Goranski in the original cast of the world premiere of the musical
Be More Chill. The show performed at the Two River Theater from May 30 to June 28, 2015 at the
Two River Theater in Red Bank, New Jersey. Canonico portrayed Schindewulf in David Chase's film debut
Not Fade Away which was released on December 21, 2012. He also appeared in
Stuck as Caleb. Canonico also was an understudy for the role of Evan Hansen in the musical
Dear Evan Hansen, which ran at the Off-Broadway
Second Stage Theater from May 1 until May 29, 2016. Canonico returned to Broadway in the Tim Minchin musical adaptation
Groundhog Day, based on the Bill Murray film. Previews began March 16, 2017, at the
August Wilson Theatre, with the official opening on April 17, 2017. Canonico reprised the role of Rich Goranski in
Be More Chill, which premiered Off-Broadway at
Signature Theatre Company in July 2018. The show ended its Off-Broadway run in September 2018 before transferring to the
Lyceum Theatre for its Broadway premiere in February 2019. The show has since then closed on August 11, 2019. ==Taking Chances/The Dude Ranch/Lion in The Mane/Parader==