The 121-bedroom property, built in 1800, has undergone a full renovation and now features conference facilities, the Fire & Spice Bar & Kitchen restaurant, Indigo Bar & Lounge and an entrance to Agnar Sverrisson and Xavier Rousset's Michelin-star restaurant Texture.
British Hospitality Association (BHA) chief executive Ufi Ibrahim officially unveiled the former Best Western Premier Mostyn Hotel.
"At the BHA, we are delighted to see the continued growth of such a welcoming hospitality brand as DoubleTree by Hilton throughout the UK, not to mention the expansion of the internationally recognised and respected name of Hilton Worldwide. DoubleTree by Hilton London Marble Arch is a superb example of the high quality accommodation and friendly welcome that characterises the experience of domestic and international visitors to London and Britain, as a whole," she said.
The opening is the latest development for one of the fastest-growing Hilton Worldwide brands which now boasts seven hotels in the capital and announced in August it would expand to Liverpool next year.