The conversion of the former London jazz house venue was announced in 2010 when owner Arab Investments declared the final hotel would be of a higher standard than any other five-star property in the capital.
Containing 36 bedrooms and suites, the luxury hotel, with interiors designed by Fox Linton, will also feature a cigar lounge and terrace, a jazz room and F&B offerings in the shape of The Crystal Bar and The Oval Restaurant.
"We are delighted to be creating one of the most high quality suite hotels in London," Khalid Affara, managing director of City and Country Hotels, the Arab Investments' company behind the development, said.
"The location of the hotel and size of (the) 36 rooms determined that the product is not only elegant and private but the service and restaurant and bar offerings will be second to none, we are very much looking forward to the opening of The Wellesley," he added.
Arab Investments currently owns a number of office and residential buildings in London as well as the The Great Western Burns Hotel in Kensington.
A spokesperson for Bespoke Hotels confirmed to BigHospitality that the company would be taking on the operation of The Wellesley on a 'white label' basis - it already manages 10 Manchester Street, Wyck Hill House in Stow-on-the-Wold and The Royal Hotel, Cardiff for Arab Investments.
The 40-cover Oval Restaurant will focus on 'refined Italian cuisine' while afternoon tea will be served in the jazz room which will contain nods to the building's musical heritage and will host live music. The Crystal Bar will also feature 1920s furniture and design and will offer a full drinks menu with a focus on whiskies and cognacs.
The rooms in The Wellesley, situated over six floors, range from Queen Rooms to the four bedroom presidential Wellesley Suite which boasts views of Hyde Park, its own boardroom and a collection of exclusive cigars.
Cigars will be showcased throughout the venue when it opens next month; a heated cigar terrace and a cigar lounge, said to include the UK's largest bespoke humidor and biggest collection of cigars sold on a stick-by-stick basis, both feature in the hotel.