The first ceremony in William’s decade-long £50 million global environmental competition will be broadcast on BBC One.
Organisers said the event, which will also be televised internationally, will feature “some of the world’s leading performers, all committed to repairing our planet”.
William, who hopes Earthshot will become the Nobel prize of the environmental world, announced the October 17 ceremony in a trailer filmed by a drone camera.
The duke, in open-necked blue shirt, was seen standing alone in front of the ornate Alexandra Palace Rose Window as the drone zoomed away from him before panning round to capture the London skyline.
The footage is being shown on London’s Piccadilly lights landmark in Piccadilly Circus at 8am on Friday.
The duke says: “Join me for the first ever Earthshot Prize Awards, where we’ll unveil five global prizewinners and their game-changing solutions to repair our planet, on October 17th, here in London,” William said.
The prize takes its inspiration from the late US president John F. Kennedy’s ambitious Moonshot lunar space programme of the 1960s, which helped advance mankind’s technological achievements.
It features five categories, or Earthshots, which organisers say if achieved by 2030 would improve life for all.
Every year from 2021 until the end of the decade, winners of the five Earthshots will each receive £1 million to be used for their solutions.
William said, to mark the venue announcement: “By hosting the Cop26 conference in Glasgow just weeks after our inaugural awards, the UK is helping lead the world in tackling climate change.
“London is a fantastic location to showcase this leadership, spotlight the finalists and award our very first Earthshot Prize winners.”
The duke met London mayor Sadiq Khan, who welcomed the ceremony as a “momentous occasion” for the city, at Kensington Palace last week.
Sir David Attenborough, who has supported the project from the beginning, is a member of the Earthshot Prize council, which will choose the winners, and fellow judges include actress Cate Blanchett, singer Shakira and queen Rania of Jordan.