Griffin led Washington to a 31-6 victory after completing 14 of 15 passes for 200 yards and four touchdowns. He also rushed for a game-high 84 yards on 12 carries.
It’s the second time this season that Griffin has earned the honor.
He was named NFC Offensive Player of the Week following his season-opening performance in a victory over New Orleans.
In that game — a 40-32 victory over the Saints — Griffin completed 19 of 26 pass attempts for 320 yards and two touchdowns, and also rushed for 42 yards on 10 carries.
Griffin is the first rookie to earn the honor twice in once season since the award was created in 1984, according to the NFL.