Davis was born in Davenport, Iowa, and attended Davenport North High School. She is a skilled violinist and attended Loyola Marymount University, graduating with a degree in music in 2006.
Davis appeared alongside teen actress Hilary Duff in Raise Your Voice. She has also appeared in Veronica Mars, That's So Raven, The O.C., Gilmore Girls, Point Pleasant, Pushing Daisies, and Hidden Palms.
In July 2007, The Hollywood Reporter announced that Davis would be joining the second season of the TV series Heroes, as Monica Dawson, who was described as a "young hero" willing to "give up everything to help the people around her". The character is the niece of D.L. Hawkins and first cousin of Micah Sanders. She has the power of muscle mimicry, meaning she can master instantly any physical skill she witnesses.
Davis played the role of Peyton in the hit film Coach Carter (2005) alongside Ashanti. She also starred as Lisa Hines in Prom Night (2008). Davis played Chastity Church in the ABC Family series 10 Things I Hate About You (Gabrielle Union played the character in the film) appearing in all 20 episodes. According to series creator Carter Covington, Davis asked out of her contract after the 20 episodes to explore new career opportunities, so Chastity was written out as transferring to a new school; the show was cancelled shortly after the episode aired.