He averaged 5.4 yards on 22 carries in the 22nd career 100-yard rushing game with the Dolphins, the most in team history.
It was the fourth POW honor in Williams' ninth NFL season, and the first time he scored receiving and rushing touchdowns in the same contest.
Other AFC honors went to New England cornerback Leigh Bodden (Defense) and Kansas City kick returner Jamaal Charles (Special Teams).
Bodden made three tackles and a career-high three pass interceptions, including a 53-yard interception-touchdown return, in the Patriots' 31-14 win over the New York Jets.
Charles scored on a 97-yard kickoff return in the Chiefs' 27-24 overtime win over Pittsburgh.
Bodden and Charles both are first time POW honorees.