In 2012, Simmons starred in the film Fat Kid Rules the World, and guest starred in an episode of Jane by Design. In 2013, she appeared in an episode of Vegas and began playing Rebecca Bowman, a rebellious Amish girl on the Cinemax series Banshee. She originally auditioned for the role of Deva Hopewell, but: "They said, 'She's too old or too sexy' or whatever". While in Philadelphia for her grandmother's funeral, the producers asked her to go back to New York to read for Rebecca, after which she won the role. In March that year, she appeared in a pictorial in Maxim magazine.