O'Hagan began her career with radio and television voice overs, most notably the narrator of the ID Channel's series
Stolen Voices, Buried Secrets. Her first television role was on the MTV series
Warren The Ape,. Director
Sean Baker has given O'Hagan roles in three of his films including the award-winning
Starlet. O'Hagan re-teamed with Sean Baker and Chris Bergoch for her breakthrough role in
Tangerine, playing Dinah, a hapless prostitute for which she achieved positive critical notices for her performance. In 2024, she had a role in another Baker film
Anora. On the Showtime series
Homeland she had a recurring role as Clarice. In 2018 she starred as Margaret in the film
Back At The Staircase which premiered at the Slamdance Film Festival. The same year she played Robert Mapplethorpe's assistant in the film
Mapplethorpe, directed by Ondi Timoner which premiered at the Tribeca Film Festival. O'Hagan guest starred in the TNT miniseries
I Am The Night in January 2019. == Filmography ==