Ramsay and Webb met at a party in high school and began playing music together shortly thereafter. They recruited Casselman, who was a friend of Ramsay's from church, to join the band in 2002. Johnston joined the band in 2004, after Ramsay saw her perform at a local open mic night.
The band released their debut album, Fix Me, in 2006. The album was a commercial success, reaching number one on the Canadian Albums Chart. The band has released four more studio albums since then: Masterpiece (2009), Ever After (2011), Astoria (2015), and Phantoms (2019).
Marianas Trench has won numerous awards, including three Juno Awards and two MuchMusic Video Awards. The band has also been nominated for a Grammy Award.
The band's name comes from the Mariana Trench, the deepest point in the Earth's oceans. Ramsay said that he chose the name because it represented the band's goal to "reach for the stars and always push ourselves to the limit."