With Mike Van Ryn in the penalty box for holding, Williams beat Ed Belfour with a wrist shot over his right shoulder. Scott Walker and Erik Cole also scored for Carolina, which improved to 17-0 this season when leading after two periods.
Carolina also moved to 4-1 against Florida this season and 10-3 the past two seasons. The Hurricanes beat Florida 6-4 Thursday night after trailing 3-0 after two periods.
Olli Jokinen and Nathan Horton scored for the Panthers, who were playing the 1,000th game in franchise history.
John Grahame, making his first start for Carolina in nine games, stopped 18 shots.
Belfour made 24 saves for Florida, which lost at home for the first time in five games.