Cousins, in his second game back from a hamstring injury that kept him out of the senior team for five matches, will undergo surgery late on Monday to repair a spiral fracture in the metacarpal bone of his left hand.
The injury was sustained in the opening minutes of Richmond's loss to Port Adelaide on Sunday.
"It was an extraordinary effort for Ben to play out the remainder of the match after being hurt so early," Richmond football operations manager Ross Monaghan said.
"We are hopeful he will only be out for one match."
Cousins, 30, went on to collect 24 possessions (10 of them contested) and was among the Tigers' best players.
The injury will prevent Cousins from playing in the Dreamtime at the 'G clash against Essendon on Saturday night.
