The Newcastle was handed a three-match ban but he denied the charge.
The ban related to an incident involving Wanderers striker Johan Elmander when Williamson appeared to head-but the player.
The FA insist the charge stands - but they won't increase it to FOUR games - something they were entitled to do.
Williamson becomes the second man from the club to be charged with the same offence on video evidence in less than a fortnight.
Midfielder Joey Barton is currently serving a three-match ban for punching Blackburn's Morten Gamst Pedersen in the chest during his side's 2-1 home defeat on November 10.
Newcastle will at least welcome back Cheik Tiote, who was suspended for the Bolton game after picking up his fifth booking, for the visit of the champions.