In 2010, O'Brien starred in the sixth series of the BBC school drama "Waterloo Road" as Bex Fisher, the eldest daughter of the new headteacher Karen Fisher (Amanda Burton). In 2010, she also appeared in "The Secret Diaries of Miss Anne Lister", in which she played the character of Miss Browne, a role which required her first on-screen lesbian kiss. Later in 2010, she appeared as a character in new television drama "The Accused" written by Jimmy McGovern, as well as starring in the 2010 series of "Strictly Come Dancing". ] Her partner was Jared Murillo and she was unable to perform in the 3rd week due to illness. She was eliminated in the 5th week of the competition after failing to impress the viewers with her Argentine Tango. She fell into the bottom two alongside Felicity Kendal who was saved thanks to the public vote.