He was selected by the Arizona Cardinals in the second round of the 2004 NFL draft, and has also played for the Miami Dolphins, the Cleveland Browns, and the Cincinnati Bengals.

Dansby was an All-State linebacker and wide receiver at Woodlawn High School in Birmingham, Alabama, where he was a letterman in football, basketball, and track.

He caught 51 passes for 857 yards and five touchdowns on offense, 81 tackles, six sacks, three interceptions, and two fumble recoveries on defense as a senior.

[7] Head coach Dennis Green named Dansby the backup outside linebacker to start the regular season in 2004, behind Levar Woods and James Darling.

Dansby recorded four combined tackles and made his first career sack on quarterback Michael Vick during a 6–3 loss at the Atlanta Falcons in Week 3.

On November 14, 2004, Dansby recorded five solo tackles, deflected a pass, and made two sacks on quarterback Kurt Warner before exiting in the fourth quarter of the Cardinals' 17–14 victory against the New York Giants in Week 10.

Dansby finished his rookie season in 2004 with 60 combined tackles (43 solo), five sacks, five pass deflections, an interception, and a forced fumble in 15 games and 11 starts.

He started in the Arizona Cardinals' season-opener against the New York Giants and recorded three solo tackles, two pass deflections, two interceptions, a sack, and scored the first touchdown of his career during a 42–19 loss.

[11] In Week 7, he collected a season-high 11 combined tackles (nine solo) and made a sack in the Cardinals' 20–10 victory against the Tennessee Titans.

On December 24, 2005, he made four solo tackles, a pass deflection, and returned an interception by quarterback Mike McMahon for an 11-yard touchdown in a 27–21 win against the Philadelphia Eagles.