After graduating from high school, Kelly returned to Los Angeles with her father to pursue acting as a hobby while she went to school to become a surgical technician. However, after her first acting class she got "hooked" and began pursuing acting as a career. Success came slowly, and she began her career with small roles in various movies and shows, including the film State's Evidence, and a recurring-guest role on the TV program What I Like About You.In the spring she was cast as Lyla Garrity on the show Friday Night Lights. In preparation for the role, she trained with the Pflugerville High School cheerleading squad.Kelly has received praise for her acting on Friday Night Lights, with the New York Times calling her performance "heartbreaking".She shot a cameo for The Kingdom, alongside Jamie Foxx. Peter Berg, the creator and pilot director of Friday Night Lights, directed the film.Kelly is the lead actor on the CW's new pilot Body Politic.