The young prince was photographed looking intrigued as he handled the fossilised tooth from an extinct Carcharocles megalodon – one of the most feared predators to have swum in the seas.
The giant shark tooth given to George was found by Sir David during a family holiday to Malta in the late 1960s.
It was embedded in the island's soft yellow limestone, which was laid down during the Miocene period some 23 million years ago.
Carcharocles megalodon is believed to have grown to 15 metres in length, which is about twice the length of the great white shark.
Sir David presented the seven-year-old with the gift on Thursday after he attended a private viewing of his new environmental documentary with the Duke of Cambridge.
Prince William and the veteran broadcaster watched A Life On Our Planet at a social distance and in the open air.
The duke and Sir David were given directors' chairs with their names printed on the back, but they decided to sit in each other's seats.
The 94-year-old broadcaster chatted to William, Kate and their three children George, Princess Charlotte and Prince Louis after the screening.
William interviewed Sir David at the World Economic Forum in Davos, Switzerland, last year, and during the discussion the broadcaster warned that humanity needed to act so that they did not “annihilate part of the natural world”.
The two men continue to support each other in their mission to tackle some of the biggest environmental challenges the planet faces.
This includes working together on William's Earthshot Prize, an ambitious global environment project announced last December to combat climate issues.
David Attenborough: A Life On Our Planet premieres in cinemas on Monday and will launch on Netflix on 4 October. An accompanying book is published on 1 October.