The 2018 No.1 pick has become the 14th AFLW player to have suffered a serious knee injury in a season only into its sixth round.
Morrison managed only one match last season, having torn her ACL at training leading into round two.
Geelong coach Paul Hood said the Cats were devastated for Morrison.
“We are all gutted. I feel so sad for Nina. Footy can be a brutal game and we know that we have to pick ourselves up, stay a united group and get ready to prepare for the next game but … the group is really determined to stay tight, we have a lot of wonderful people here, wonderful players who are so united and look after each other,” he said.