Walden was sanctioned for ripping off Walker's helmet during an altercation in the Colts' 30-27 victory last week and striking him in the head while still wearing his own helmet.
Walden wasn't ejected after the incident, instead receiving a personal foul penalty.
He will miss Sunday's game against Arizona if the suspension is upheld after an appeal.
Walden has 28 tackles and two sacks in 10 games for Indianapolis this season.
Notable deaths of 2014 [PHOTOS]