Following the post, a spokesperson from World Animal Protection reached out to news.com.au to express concern, revealing that the cuddly marsupials "experience distress when handled by humans" and slamming the star's "disregard" for their wellbeing.
The video sees Wilson doing "15 kilo squats" while holding a large wombat close to her chest as she faces the camera.
"Wombat squats! Thanks to the team @thesydneyzoo for organizing this fun workout and education sesh about some amazing rescue animals," the actress wrote to her 8 million followers.
Executive director Simone Clarke said wildlife experts from World Animal Protection were "disappointed" to see the footage.
"We are disappointed to see Rebel Wilson handling Australian wildlife with such disregard for their wellbeing," she wrote in a statement.
"Wombats are not a photo prop or plaything; they are sentient beings, and experience distress when handled by humans.
She went on to condemn the zoo for allowing the workout content to be filmed.
"It's appalling that Sydney Zoo endorse this type of promotion – quite frankly they should know better."
In the comments on the post, some followers echoed the same sentiment.
"Is it really needed to grab a hold of a wombat!?!," one said.
"Yeah....I felt a little uncomfortable for it....," another responded, while one more weighed in: "(100 per cent) animal exploitation. I thought better of her. Maybe just a silly mistake and not thinking!"
News.com.au has reached out to Rebel Wilson's management for a statement.
The Isn't It Romantic star publicly made a New Year's resolution at the start of the year to ditch her unhealthy eating habits and kickstart a new fitness journey.
She wrote on Instagram: "Okay so for me 2020 is going to be called 'The Year of Health'.
"So I put on the athleisure and went out for a walk, deliberately hydrating on the couch right now and trying to avoid the sugar and junk food, which is going to be hard after the holidays I've just had but I'm going to do it! Who's with me in making some positive changes this year?"
In an interview with E! earlier this year, her trainer Jono Castano explained he had created a specific program for Wilson covering six days.
He said he encourages his clients to workout daily for 45-minute sessions, noting "results come through consistency".
His personalised program for the star included high-intensity interval training, mobility, weights, resistance, technique and tempo. Wilson has one day off a week to rest her body.
