Dockett attended Florida State University, where he played for coach Bobby Bowden’s Florida State Seminoles football team. After an early season injury, Dockett redshirted his first year at Florida State, as the Seminoles went wire-to-wire as national champions in 1999. In 2000, they had to replace interior defensive linemen Corey Simon and Jerry Johnson in the starting line-up. Dockett successfully secured a spot, starting the last 10 games of the year at defensive tackle. He recorded 66 total tackles (including 32 unassisted), which was most of any freshmen on the team, and tied for the team lead in tackles for loss (19). Dockett also added a team-high 18 quarterback hurries, and seven sacks (third on the team). His performance earned him freshman All-America honors, and he was named the freshman defensive player of the year by Football News.

Dockett was selected to start in the 2010 Pro Bowl as a Defensive Tackle.

On September 1, 2010, the Cardinals signed Dockett to a 6-year, $56 million contract extension, with $30 million guaranteed. This would have kept him with the franchise through the 2015 season. During the press conference, Dockett stated that he wanted to “retire an Arizona Cardinal”.

On August 18, 2014, Dockett tore his ACL, ending his 2014 season.

On February 27, 2015, the Cardinals released Dockett.

On March 5, 2015 Dockett agreed to a two-year, $7.5 million contract with the San Francisco 49ers, however on September 4, 2015, Dockett was released.

On July 24, 2016, it was announced that Dockett would retire. The next day, he signed a one-day contract to retire with the Cardinals.