She also played Tina Edison in the Canadian sitcom Maniac Mansion (1990–1993) and Clare Arnold in the Fox teen drama series Beverly Hills, 90210 (1994–1997).

[5] In 1997, her then-boyfriend, director Gregg Araki cast her as Lucifer, one of a group of bored, alienated, and very horny Los Angeles teens in the black comedy drama film Nowhere.

[5][7] She later appeared in a number of independent films, and had guest-starring roles on Law & Order: Criminal Intent, Medium, CSI: Miami, and Rookie Blue.

[2] In 2011, she was cast as Kitty O'Neill, Tom Kane's personal aide alongside Kelsey Grammer in the Starz original drama series Boss.

[9] Robertson also starred in a number of made-for-television movies in recent years, primarily for Lifetime network, including Last Exit (2006), and Time of Death (2013).

In 2013, Robertson was cast as the lead in the TNT detective drama series Murder in the First co-created by Steven Bochco which debuted on June 9, 2014.

In the same year she starred in the thriller film The Vatican Tapes that was released on February 27, 2015,[16] and was cast in recurring role as Jodi Morgan for the second season of A&E drama series Bates Motel.

[20] In 2015, Robertson completed the Writers Guild's Showrunners Training Program, where she was mentored by former WGA West president John Wells.

[21] In 2017 she began adapting The Possibilities, Kaui Hart Hemmings' follow up novel to The Descendants about a grieving Colorado mother whose son was killed in a skiing avalanche and then starts a friendship with a mysterious young girl.

She also sold a new series to CBC called APRES SKI as well as a show to Lionsgate with Academy Award nominated doc filmmaker Joe Berlinger attached to direct.

She gave birth to her first child, a son named William Robertson Cowles, on July 9, 2008, at Cedars-Sinai Medical Center in Los Angeles.