During a recent trip to Greenland, the Tasmanian-born beauty stepped out in a sealskin, knee-length coat by local designer Great Greenland.
The winter trench, which was designed by Jesper Høvring and shown on the runway at Copenhagen Fashion Week earlier in the year, features several panels of seal skin across it.
Since her appearance, many animal rights activists have slammed the mother-of-four for wearing the ensemble.
“I like Princess Mary, but that’s horrible,” one user proclaimed.
“I thought she would have been a little more aware than this,” another noted.
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Speaking to Woman's Day Online, PETA Australia’s Associate Director of Campaigns Ashley Fruno said the royal should think twice before donning fur.
"Despite being made aware of all the cruelties of the fur industry, it still hasn't clicked for Princess Mary that wearing animals makes her look cold-hearted and totally out of touch."
"Seals used for fur are often bludgeoned, dragged across the ice, and thrown into a pile to choke on their own blood before being skinned, sometimes alive. The majority of Australian people shun fur, and it's time that the princess gave animals a fair go by going fur-free," Ashley Fruno said.
Meanwhile, others have defended Mary and pointed out the fact she regularly sports ethically-sourced ensembles.
“Princess Mary often wears ‘ethical clothing’, wearing seal is to support the industry in Greenland. Seals, like cows, are used for their meat and fur. This is like someone criticising Kate’s knee high leather boots,” one user said.
“They’re just jealous she looks so good in it. And heck, at least it wasn’t made from baby seals,” another person added.
In a recent interview with Vogue Australia, the 44-year-old spoke passionately about sustainability in the fashion industry.
“I believe that in order to find solutions to some of the most pressing global challenges of today we need to take a holistic approach that requires us to consider the social, environmental and economic aspects and work together in new and innovative partnerships, maybe with people and organisations we wouldn’t have thought about working with before," she told the fashion publication.
"It will require a continuous effort and patience, and strong and authentic leadership: it takes time to create real and sustainable change."
Princess Mary is yet to comment on the situation.