In film, Cornish is known for her roles as Heidi in Somersault (2004), Fanny Brawne in Bright Star (2009), Sweet Pea in Sucker Punch (2011), Lindy in Limitless (2011), Clara Murphy in RoboCop (2014), and Sarah in Geostorm (2017).

In April 2010, Cornish was cast in Limitless, the film adaptation of the novel The Dark Fields,[7] directed by Neil Burger and also starring Bradley Cooper and Robert De Niro.

In 2015, she played Agent Katherine Cowles in Solace, a mystery thriller film directed by Afonso Poyart with central performances by Anthony Hopkins, Colin Farrell, and Jeffrey Dean Morgan.

[13][14] In 2017, she played Agent Sarah Wilson in the science fiction disaster film Geostorm, directed, co-written, and co-produced by Dean Devlin, also starring Gerard Butler, Jim Sturgess, Ed Harris, and Andy García.

[15] In 2019, she starred in the Australian television miniseries Secret Bridesmaids' Business along with Katie McGrath and Georgina Haig.

[18] The same year, she released two new tracks on SoundCloud: "Evolve" featuring Jane Tyrrell and "Way Back Home", which was produced by Suffa from Hilltop Hoods.

She is committed to cruelty-free eating,[20] and in 2006, became an ambassador for Australian animal rights group Voiceless, the animal-protection institute, and was part of a national advertising campaign in 2012.