Janet Montgomery began her acting career at age 12, when she featured with her brother in the British children's show Short Change. After a one-episode appearance in the teen series Skins, as well as a few short films, she moved to Los Angeles to pursue more opportunities.
Montgomery got her biggest break when she starred in the direct-to-DVD horror flick The Hills Run Red; while the film was generally panned her performance received plaudits. After appearing in other films such as Dead Cert and the critically acclaimed Black Swan, she joined the cast of Entourage for a recurring role, and later, the Fox series Human Target.