The NHL announced the discipline Friday.
Thornton was ejected from Thursday's game in St. Louis after hitting Perron in the neutral zone. Thornton had just come out of the penalty box and Perron didn't appear to see him before getting hit.
The only other player to be suspended under Rule 48 is Phoenix Coyotes captain Shane Doan, who received a three-game ban last month. Two others have received a $2,500 fine.
Thornton was surprised to be thrown out of Thursday's game, saying "he just ran into me, to be honest with you."
He will be eligible to return Thursday against the New York Islanders. He will forfeit more than $77,000 in salary.