Cook graduated from Palm Beach Gardens Community High School where he rushed for 2,027 yards and 27 touchdowns as a senior and was recognized as the South Florida Sun-Sentinel Player of the Year for large schools. He led his team to the Class 6A state title as a senior, marking the first state championship in school history. Cook ran for 373 yards and five TDs in a game against Atlantic, busted a 99-yard run vs. Lake Worth in the playoffs, and rushed for 243 yards and four scores in the state title game.
In 2008 Cook was the team's leading tackler but was declared academically ineligible for the Outback Bowl. His 2008 totals were 97 tackles (62 solo) and one interception. In 2007 he earned second-team All-SEC honors by the SEC coaches, the Associated Press, and Rivals.com. He led the team with 92 tackles, including 77 solos, including eight for losses. He also had 4 sacks, 3 interceptions, 5 passes broken up and forced 2 fumbles. In 2006 he earned freshman All-SEC honors by both the league's coaches and the Sporting News and tied for third on the team in tackles with 47, including 40 solo stops and five tackles for loss, despite playing only 10 games.