Renovation works were set back last June by a serious fire, which tore through part of the roof.
It follows “the most extensive” renovation in the hotel’s 117-year history, boasting new guest rooms and suites, and two brand-new penthouse suites.
“Mandarin Oriental is enormously proud of the heritage of this historic hotel,” said Amanda Hyndman, general manager and area vice-president of operations.
“The scope and intricate detail of this momentous renovation is designed to ensure this iconic London establishment is recognised as one of the finest hotels in the world.
“We look forward to welcoming our guests with kind and intuitive service that is truly British but reflective of our Oriental heritage.”
Around 120 firefighters attended the fire on 6 June last year, which London Fire Brigade said spread over several floors. Nearly 300 guests and staff were evacuated from the building, but there were no reports of any injuries.
Designer Joyce Wang has overseen the redesign of all 181 guest rooms and suites, now adorned with art deco features, curated artwork and bespoke furniture, designed to take advantage of the hotel’s views of Hyde Park and the wider central London skyline.
A new spa, meanwhile, features 13 individual treatment rooms, two massage beds and a water temple, while the hotel’s Dinner by Heston Blumenthal restaurant has been refurbished, as has its bars.