The Duke of Cambridge, 32, mingled with guests including newly-married Katherine Jenkins, Kate Silverton and Deborah Meaden at the Tusk Conservation Awards in London's Claridge's Hotel.
William is the royal patron of Tusk, which helps to save African wildlife from extinction. It's a cause close to his heart, and the Duke was on hand to present the evening's top prize to Madagascan conservationist Herizo Andrianandrasana, who has helped islanders personally get involved in conserving almost 900,000 acres of land.
It was the second annual Tusk Awards, hosted again by BBC presenter Kate, and William told the invitees, "The work of this year's finalists serves to illustrate some of our greatest conservation challenges: dramatic loss of lion, poaching of elephant and rhino; deforestation and the critical need for community involvement."
Announcing plans to add a third award for wildlife rangers, the royal added, "Wildlife rangers are the men and women at the frontline if the battle – and it is a battle – to save some of the world's most iconic species.
"These people cannot face the bullets and the threats alone. It is up to governments and intra-national bodies to unite behind them, and to play a meaningful part in ensuring that their efforts on the ground are fruitful."
William has been patron of the Tusk Trust since 2005, and has previously spoken about how his late mother Princess Diana inspired him to help Africa's wildlife.
"She would come back with all these stories and full of excitement and just passion for what she had been doing," he said in an interview with CNN. "And I sort of used to sit there, quite a surprised little boy at the time, taking it all in."