Walker (groin) has been ruled out for Sunday's game against the Falcons, Jordan Schultz of Fox Sports reports.
Walker was a late addition to the Chiefs' practice report Friday as a DNP due to what was described as "groin tightness." He was initially tagged as questionable for Sunday's contest, but the injury is severe enough for the fifth-year running back to miss his first game of the regular season. Rookie fifth-rounder Emmett Johnson is projected to lead Kansas City's backfield against Atlanta in Walker's absence, and with Jaydn Ott (hamstring) listed as questionable, the Chiefs could elevate Nate Carter from the practice squad to the active roster. Walker's next opportunity to play is Week 11 against the Cardinals on Sunday, Nov. 22.