Crilly was educated at Kent College, Pembury, and attended Middlesex University, where she studied performing arts.
She stars in the BBC children's comedy series Sorry, I've Got No Head, alongside William Andrews, James Bachman, Marcus Brigstocke, Mel Giedroyc, Marek Larwood and Nick Mohammed.
In December 2008 Crilly was nominated for a British Comedy Award as Best Female Newcomer for her portrayal of Magda in Lead Balloon, but lost out to Katy Brand.
[citation needed] She has also starred in Pixelface, a comedy for children, as a waitress zombie slayer called Claire Parker.
Crilly plays the lead role as Coma Girl in Channel 4's Comedy Showcase, again alongside Katy Wix.