Hilton Worldwide global head of luxury and lifestyle brands John Vanderslice said: "Waldorf Astoria Hotels & Resorts has applied its values of timeless elegance and extraordinary service to our first London-based Waldorf Astoria property, which is completely unique with its beautiful location."
Guests enjoyed a tour of the hotel and its herb garden by executive chef Lee Streeton.
Tourism minister John Penrose MP, who attended the event, said: "I’m delighted to see Waldorf Astoria Hotels & Resorts developing its presence in Britain with what is a wonderful addition to our luxury offering. With our aim to attract four million extra visitors over the next four years it’s unique properties such as this that will provide people with more reasons to visit."
London Syon Park, A Waldorf Astoria Hotel features 137 guest rooms and is set in 200 acres of parkland.
The Grand Syon Ballroom can host as few as 100 or as many as 450 guests.