In China, when Yao Ming speaks, people listen. Trading on this former basketball superstar’s towering stature in his home country, WildAid has named Mr. Yao a spokesman on behalf of Africa’s severely threatened elephant and rhino populations to help curb China’s multi-billion-dollar lust for illegal wildlife products.

“Saving Africa’s Giants With Yao Ming,” Tuesday on Animal Planet, follows Mr. Yao to the Samburu National Reserve in Kenya and the Kariega Game Reserve in South Africa to witness the brutality inflicted by poachers upon these creatures. Some of the images are heartbreakingly graphic. So are the statistics, about the six northern white rhinos left in the world (the seventh died last month), their horns believed by some cultures to contain medicinal properties, or the more than 20,000 African elephants killed in 2013 for ivory to be carved into trinkets. With a demand that exceeds the number of animals remaining, “it’s a race against time to get people to care sufficiently,” says Iain Douglas-Hamilton, the founder and chief executive of Save the Elephants. Or, as Mr. Yao says in a public-service spot, “When the buying stops, the killing can, too.”