Gryner started her music career in Toronto, where her original song "Wisdom Bus" won a nationwide songwriting contest sponsored by Standard Broadcasting.

The gig saw Gryner performing with Bowie at Glastonbury Festival, on Later with Jools Holland, Saturday Night Live, and other venues around America and Europe.

The Summer of High Hopes, produced by Nathan Larson, was released in Canada and later in Ireland on the heels of a performance at Oxegen Festival; The Irish Times' Siobhàn Long said it was "the distilled voice of an original".

[12] In the November 2006 issue of Q, U2 frontman Bono recognized the track "Almighty Love" as one of six songs that he wished he had written from the last twenty years of music.

[16] In May 2013, Gryner arranged and performed piano on astronaut Chris Hadfield's cover version of David Bowie's "Space Oddity".

[18] Fanshawe College presents an annual Emm Gryner and Chris Hadfield Music Industry Arts Award to a Year 2 student in the School of Contemporary Media who demonstrates "a keen interest [...] in the creative and technical aspects of the music industry [and] leadership characteristics with respect to his or her classmates, faculty and staff, as well as exceptional creativity and dedication".

She is also a member of the collective The Cake Sale, along with Gary Lightbody of Snow Patrol, Bell X1, Josh Ritter and Glen Hansard.

Gryner performs her ballad-style cover of Def Leppard's Pour Some Sugar On Me, arranged for the Royal Philharmonic Orchestra by Eric Gorfain, with the band on their album Drastic Symphonies.

In October 2016 Gryner starred in Joni Mitchell: River at the Grand Theatre in London, Ontario along with Louise Pitre and Brendan Wall.

[27] The play and performers met with positive reviews: in the London Free Press Joe Belanger commented that "her vocal range, the emotional qualities of her voice and its sound [are] like a touchstone to Mitchell throughout,"[28] and Mary Alderson wrote that "she is stunning in her a capella numbers".