She began her career on daytime television, playing Lucy Montgomery on the CBS soap opera As the World Turns from 2001 to 2005, before she went to primetime with regular roles on the short-lived dramas Windfall (2006) and Big Shots (2007).

She also starred on a recurring basis as Poison Ivy in the Fox crime drama series Gotham (2018–2019), and voiced the character in the 2019 animated film Batman: Hush.

The following year, she played a small part in an episode of Law & Order: Special Victims Unit, and started a three-year run as Lucy Montgomery on the CBS soap opera As the World Turns.

During the 2007 pilot season, List was cast in another ABC series, Big Shots, in which she played the role of Cameron Collinsworth, daughter of Dylan McDermott's character.

List also guest-starred on several television shows, including Moonlight, Ghost Whisperer, CSI: Crime Scene Investigation, Monk, Hawaii Five-0, and House of Lies.

From 2008 to 2013, List appeared in a recurring role on the AMC series Mad Men, playing Don Draper's fill-in secretary who later became Roger Sterling's second wife.

The following year, she had recurring roles in the CW series The Flash and in ABC's short-lived prime time soap opera Blood & Oil.