Ewell co-starred in The CW television series The Vampire Diaries for the first seven episodes in 2009. Ewell described her character, Vicki Donovan, to Star magazine as "a really slutty high school student", and "a troublemaker".[4] Vicki was the first human on the series turned into a vampire. Ewell was killed off the show when her character was staked in the heart by Stefan (Paul Wesley) in order to save Elena (Nina Dobrev) in the Halloween-themed episode "Haunted".[5] Ewell hinted in November 2009 that she was still under contract for the role and might return to the show, but series creator, Kevin Williamson, stated that there were no plans to bring her back.[6] Her character did return however in several episodes as a ghost on the “other side”, she featured in the finale of the second season, the start of season 3 and was a major feature role in the series finale of The Vampire Diaries (season 8) when she is briefly brought back from the dead by the titular Vampire Katherine Pierce to help her destroy the town of mystic falls.[7][8]
Ewell starred in the horror film The Demented (2013) alongside Sarah Butler and Michael Welch.[13] She also starred in the 2014 Lifetime movie, Deadly Daycare, with Christy Carlson Romano. In April 2016, Ewell began filming the feature, 2 Years and 8 Days, with Ryan Merriman in New Mexico.[14] The film, retitled 2 Years of Love was released on January 24, 2017.
She portrayed Nora Truman (formerly named Mara) in The CW 2019 television series Roswell, New Mexico. In 2020, Ewell guest starred on CW's Batwoman as the DC comics villain Nocturna.[15]
In May 2015, she got engaged to actor and model Tanner Novlan.[17][18] The couple married on September 12, 2015.[19]
In March 2019, Ewell announced that she and her husband were expecting their first child.[20] On July 16, 2019, Ewell gave birth to their first child, a daughter named Poppy.[21] In February 2022, Ewell announced that she and her husband were expecting their second child.[22] On June 6, 2022, Ewell gave birth to their second child, a son named Jones.[23]