During the evening the Duke of Cambridge presented two awards, a lifetime achievement honour called The Prince William Award for Conservation in Africa, was awarded to Clive Stockil and another accolade which recognises up-and-coming conservationist was won by Tom Lalampaa.
Kate has been seen in public since giving birth to Prince George on 22 July when she attended the The Ring O'Fire Marathon in Anglesey, although Thursday night's appearance was her first official engagement.
Africa holds a special place in the royal couple's heart after William proposed to Kate at a remote safari lodge in Kenya.
The Prince has long been involved with the work carried out by Tusk Trust and was made the charity's royal patron in 2005.
The ceremony was also filmed for a new documentary, airing on 15 September, which features new-dad William speaking about his passion for conservation coupled with his hopes for his family.