The star made the comment after reposting a breaking news story from WildAid on how Vietnam has banned all imports of wild animals, dead or alive, to reduce further pandemic risk.
Vietnam's Prime Minister Nguyen Xuan Phuc has also called for tougher action against people involved in illegal hunting, killing, or advertising of wild animals in a new directive with immediate effect.
'This is huge'
DiCaprio, who often uses his platform to raise awareness of meat's environmental impact, said to his 45.1 million Instagram followers: "This is huge for both the protection of wildlife and ourselves.
"We must end the trade. #EndTheTrade #WhenTheBuyingStopsTheKillingCanToo #WorthMoreAlive."
Is Leonardo DiCaprio Vegan?
Whilst DiCaprio has invested in plant-based brand Beyond Meat, and executively produced the environmental documentary Cowspiracy - he is not vegan himself.
However, it was reported that the celeb requested a plant-based meal for the 2020 Governors Ball earlier this year.
Chef Wolfgang Puck told Hollywood Life: "I did the SAG Awards and Leo said, 'What can you give me, something vegan?'. He wanted vegan. We made a vegan pizza. He ate it so fast. He said, 'Oh, can you bring another one?'."