Walsh has recovered from leg and ankle injuries, but a virus has stopped him from training properly in recent days.
As a result, he is not fit enough to participate in the game against the Rabbitohs, which takes place on Sunday evening at Langtree Park.
“He won’t play. He’s not ready,” said Cunningham.
“It’s unfortunate he can’t be part of such a big event but I don’t think we can risk him.
“He’s a world-class player and he’d have a big influence on the game but we’ve a very long season and we’ll probably need him on many occasions down the track.”