Al Thornton began playing college football at Florida State University, where his impressive four-year career ended on a high note, with Thornton making the AP All-American 3rd team. He was further selected into the All-ACC 1st team, and finished runner-up to Jared Dudley, for the ACC Player of the year award. Despite leading the ACC in terms of scores, Thornton was not able to overturn the loss that the Seminoles faced at the NCAA tournament qualifiers.
Thornton began playing professionally, after he was picked by the Los Angeles Clippers, in the 14th overall, 2007 NBA draft. Sharing his agent with Yao Ming, Thornton played his first league game against the Denver Nuggets, which they lost. Thornton scored 24 points, with 1 assist, 2 blocks and 8 rebounds.
In his third preseason game, Thornton proved his mettle scoring a Clippers win against the Golden State Warriors, scoring 24 points, which included a perfect 2-2. At the start of the season, Thornton was not given much playing time, as compared preseason, mainly due to the presence of Ruben Patterson in the starting lineup. But Patterson was waived in December, 2007, giving the talented rookie more playing time. The season was marred by a number of injuries to Clipper’s big stars, including Paul Davis, Elton Brand, and Tim Thomas, giving Thornton the perfect arena to showcase his skills.
In January, 2008, in a match against the Atlanta Hawks, Thornton scored his career high 33 points, including an impressive block in the final seconds of the game. Thornton attained his first double-double, against the Philadelphia 76ers, where he scored 10 rebounds and 18 points.
In March of the same year, Thornton scored 39 points in a game against the Memphis Grizzlies, which equaled a rookie franchise record, as well as the season high for the Clippers. Following this exceptional performance, Al Thornton was awarded the NBA All-Rookie First Team, for 2008.