Shortly after the grand jury failed to indict him on both incidents in Austin, Benson signed a one-year, $520,000 contract with the Cincinnati Bengals on September 30, 2008. DeDe Dorsey was placed on injured reserve and Chris Perry was the starter. Benson's season began in a loss to the Dallas Cowboys, rushing 10 times for 30 yards. He became the starting back for the Bengals in Week 7 against the Pittsburgh Steelers. Benson rushed 14 times for 52 yards in his first career start as a Bengal, and ran over Steelers safety Troy Polamalu, giving the Pro Bowler a concussion. In the following 35–6 loss to the Houston Texans, he totaled 49 yards on 13 carries and had two receptions for 20 yards. The Bengals picked up their first victory of the season in a 21–19 game against the Jacksonville Jaguars, with Benson carrying 24 times for 104 yards and a touchdown. Benson hit his stride in the Bengals' three-game winning streak at the end of the season, gashing the Washington Redskins in week 15 with 161 yards from scrimmage, including 88 yards receiving (79 of which came on a screen pass). In week 16, Benson dominated the Cleveland Browns, rushing for 171 yards. In the final game of the season against the Kansas City Chiefs, Benson had 111 yards on 25 carries. In the twelve games he was active during the 2008 season, Benson had 932 yards from scrimmage: 747 rushing and 185 receiving.