Early in her career, she appeared in television commercials for Old Navy, Verizon, Logitech and Neutrogena. She made her television acting debut in an episode of Complete Savages, in 2005. In 2007, Stevens West began portraying Ashleigh Howard on the ABC Family comedy-drama television series Greek. In a review released soon after the premiere of the show, the Pittsburgh Post-Gazette called the show “light-hearted fun” and “authentic” while The New York Times claimed that Greek “captures the spirit of the hedge-fund age like nothing else.” The series concluded after four seasons on March 7, 2011. She has appeared in films The Fast and the Furious: Tokyo Drift (2006), Fired Up! (2009), The Amazing Spider-Man (2012), The Kitchen (2012) and Jessabelle (2014).

She has appeared in guest roles on How I Met Your Mother, Friends with Benefits, Baby Daddy, 90210, Ben and Kate and New Girl. In 2011, Stevens West played the role of Mimi Marquez in the musical Rent: Downtown L.A. She made a guest appearance as Joy Struthers on CBS’ Criminal Minds, in the episode “Fate”. In 2014, she appeared as Jonah Hill’s character’s love interest called Maya in the comedy film 22 Jump Street. The film received positive reviews, with some critics calling it one of the best comedy sequels of all time, and grossed $331 million worldwide.

Stevens began dating actor Andrew J. West after they met while co-starring in Greek. They married on December 5, 2014, in Los Angeles. The couple welcomed a daughter in October 2018.

In 2015, Stevens West co-starred opposite Jerrod Carmichael as Maxine in the NBC comedy sitcom The Carmichael Show. In 2017, following that show’s end, Stevens West was cast as a series regular on the FOX supernatural comedy series Ghosted. She portrayed a restaurant and bar designer Claire Davis opposite Damon Wayans Jr. on CBS’ comedy television series Happy Together (2018–2019). The series followed a young couple whose lives are suddenly thrown into chaos when a pop star moves into their home.