He played college football for the Central Missouri Mules and was selected by the San Francisco 49ers in the sixth round of the 2006 NFL draft.

[3] He was a first-team All-Region selection by The Times, adding All-Division and All-San Gabriel Valley honors as a senior under the direction of head coach John Capraro.

He played in the East/West All-Star game and also excelled in track & field, winning the Division III 100-meters title after also finishing first in the 2002 Miramonte League Meet.

Walker finished his junior college career with 86 catches for 1,312 yards and 13 touchdowns before transferring to the University of Central Missouri.

[9] During a Week 13 31–14 road loss to the Carolina Panthers, Walker caught his first NFL touchdown on a 21-yard pass from Trent Dilfer.

[25][26] In the postseason, Walker caught two passes for 36 yards before the 49ers lost to the eventual Super Bowl champions, the Giants, in the NFC Championship Game.

[27] During a Week 7 13–6 victory over the Seattle Seahawks on Thursday Night Football, Walker caught his first touchdown of the season on a 12-yard pass from Alex Smith.

[29] Three weeks later against the New England Patriots on NBC Sunday Night Football, he had two receptions for 34 yards and a touchdown as the 49ers won on the road by a score of 41–34.

[37] In the next game against the Houston Texans, he caught his first touchdown of the season on a 10-yard pass from Jake Locker as the Titans lost on the road in overtime by a score of 30–24.

[44] Walker began the season with three receptions for 37 yards and a touchdown in the season-opening 26–10 road victory over the Kansas City Chiefs.

[45] In the next game against the Dallas Cowboys, he had a career day with ten receptions for 142 yards and a touchdown as the Titans lost by a score of 26–10.

[46] Two weeks later against the Indianapolis Colts, Walker caught five passes for 84 yards and a touchdown as the Titans lost on the road by a score of 41–17.

[52] Walker began the season with three receptions for 43 yards and a touchdown in the season-opening 42–14 road victory over the Tampa Bay Buccaneers.

[53] During a Week 9 34–28 overtime road victory over the New Orleans Saints, he recorded his first career multi-touchdown game with seven receptions for 95 yards and two touchdowns.

He caught a pass from quarterback Zach Mettenberger, broke two tackles, hurdled a man, and stiff-armed another, all while racing down the sideline to the end zone to complete a 57-yard score.

[61] In the next game against the Detroit Lions, he had six receptions for 83 yards and his first touchdown of the season as the Titans narrowly won on the road by a score of 16–15.

[74] In the next game against the Houston Texans, he put up similar numbers, catching five passes for 63 yards and a touchdown as the Titans won by a score of 24–13.

[78][79] During the Wild Card Round against the Kansas City Chiefs, Walker was the leading receiver, catching six passes for 74 yards as the Titans narrowly won on the road by a score of 22–21.

[80] In the Divisional Round against the New England Patriots, he had three receptions for 49 yards including a 36-yard catch and run during the first quarter during the 35–14 road loss.

[85] During the season-opener against the Miami Dolphins, Walker had four receptions for 52 yards before leaving the eventual 27–20 road loss with an ankle injury in the fourth quarter.

[94] Without him, the Titans finished 9–7 for the fourth consecutive year and lost to the Kansas City Chiefs in the AFC Championship Game.

The tragedy motivated him to speak out against drunk driving, and support laws requiring the installation of an ignition interlock device for first-time DUI offenders.

[104] Walker co-hosts the weekly NFL and college football gambling show The Locker Room, presented by the Bussin With The Boys podcast, alongside former Titans teammates Will Compton and Taylor Lewan.