Marks started off her career in 2001 in the short-film G Spots?. In 2002 she had a guest starring role on Law & Order: Criminal Intent. In 2003 she had a small role in Mona Lisa Smile. In 2004, Marks starred in the independent drama, The Undeserved. She is perhaps best known for her role in the 2012 drama The Sessions alongside Helen Hunt, william H. Macy, and John Hawkes. The film received wide critical acclaim. In 2014, Marks had the lead role in the indie film Grace. and in 2015 starred in psychological drama Anguish.
In 2015, she starred in the one-woman play All American Girl, by Wendy Graf. She will co-direct the short film The Games We Play with Rich Newey, which will be her first time directing. In 2016 she starred in The Model Apartment, by Donald Margulies at the Geffen Playhouse
She filmed the independent feature The Last Champion in early 2017.
