He played college football for the Wake Forest Demon Deacons and Michigan State Spartans.

[1] He attended Arlington High School and played for their football team, where he rushed for 3,485 yards with 41 touchdowns.

[20] He was named the starting running back for the Seattle Seahawks after Rashaad Penny was placed on injured reserve.

[21] In Week 7, against the Los Angeles Chargers, Walker rushed for 167 yards and two touchdowns in the 37–23 victory.

[26] He joined Curt Warner as the only players in franchise history to rush for at least 1,000 yards as a rookie.

[27] On January 14, 2023, during the 2022–23 NFL playoffs, Walker rushed the ball 15 times for 63 yards and a touchdown, during a 41–23 Wild Card Round loss to the 49ers.