Toronto area resident Yasmin Nakhuda had gone to court to try to force a sanctuary that took in the animal -- which she described as her child -- to return it.
But Ontario Superior Court Judge Mary Vallee ruled against her.
"The monkey is not a child," Vallee said in a 13-page decision.
"The monkey is a wild animal... (and) Ms. Nakhuda lost ownership of the monkey when she lost possession."
While she was inside the store, Darwin escaped his crate inside her locked car and was spotted strolling around the furniture store's parking lot, wearing a sheepskin coat.