The Duke of Cambridge, 31, was spotted arriving at London's Zoological Society on Wednesday morning where he attended a symposium and gave a speech about the fight against illegal wildlife trafficking.
Looking dapper in a dark suit and maroon tie, William took centre stage as he spoke about how his foundation, United for Wildlife, would tackle the issue.
The prince described United for Wildlife – the partnership that is made up of seven wildlife charities – as a "powerful alliance" and called on the audience to join them in their bid to stop trafficking against elephants, rhinos, tigers and other endangered animals.
"The forces that are currently destroying some of the world's endangered species are sophisticated and powerful," said William. "But this week we are seeing the creation of an equally powerful alliance coming together to help fight them.
"The commitments set out today will begin to address the challenges of protection, enforcement and demand reduction. We will use our combined resources to make sure they succeed.
"Ours is not an exclusive partnership. It is my hope that you will all become part of United for Wildlife and the Global Alliance to stop illegal wildlife trafficking."
William was speaking on the second day of the ZSL Symposium where experts have been gathering over two days to discuss wildlife trafficking and ways to tackle it. Solutions include targeting poaching on the ground, working with local communities to stop consumer demand and strengthening protection for wildlife areas by including GPS trackers and drones.
The prince's attendance at the symposium comes just days after he and his father Prince Charles released a video message calling on people to combat the illegal wildlife trade. This is the first of three United For Wildlife events William will take part in this week.
On Wednesday night, the royal will attend a reception at the National History Museum to mark the start of London Conference on the Illegal Wildlife Trade. The following day, both Charles and William will attend the conference, when the first-in-line to the throne will deliver a speech.