Hill attended Clemson University, where he played for the Clemson Tigers football team from 2001 to 2005. He graduated with a bachelor's degree in human resource development. Hill was an All-American selection in 2005 and also a first-team All-Atlantic Coast Conference (ACC) choice. He was also a finalist for the Thorpe Award, given to nation’s top defensive back. He had three interceptions, defended 7 passes and 54 total tackles. In 2004 Hill defensed 21 passes, two tackles for a loss and a sack to go along with his 52 tackles. In 2003 he started 11 of the 13 games and had seven pass breakups and two interceptions in his first season as a defensive back while also totaling 37 tackles. In 2002 Hill was a running back and was Clemson's third-leading rusher as a freshman with 225 yards on 42 carries and led all Tiger running backs in yards per carry (5.4). In 2001 he red-shirted as a running back.
Hill was drafted in the first round (15th overall) by the St. Louis Rams in the 2006 NFL Draft. On July 31, 2006, Hill signed five-year $10.2 million contract with the Rams. In his rookie season he started in ten out of 16 games and finished the year with 50 tackles and three interceptions. Hill started his NFL career with a bang by recording two tackles and an interception, in the season opener against the Broncos. He capped the season by being named Rams Rookie of the Year and was voted to the 2006 All-Rookie honors from PFWA. For the 2007 season, he played in eight games and finished the season with 35 tackles and one interception. However, that interception was instrumental in the Rams 13-7 victory over the Divisional rival 49ers, in San Francisco on November 18, 2007. He finished the season on injured reserve. In 2008, in four starts, Hill totaled 20 tackles, 2 pass deflections, and a forced fumble. Hill tore cartilage in his knee which forced him to sit out the rest of the season after playing only four games. It was the second straight season he ended on injured resereve.
Hill was traded to the Atlanta Falcons on September 1, 2009, for a 7th round pick in the 2010 NFL Draft. Hill scored the first touchdown of his career on November 8, 2009, when he intercepted a pass from Jason Campbell and returned it for a 62-yard touchdown.