The five-AA-star Sofitel London St James is to undergo a £16m renovation of its 183 bedrooms.
The funding for the AccorHotels-operated property has been agreed as part of a wider £45m package from Barclays' Corporate Banking team in Scotland, which will include the refinancing of an existing arrangement.
French designer Pierre-Yves Rochon will oversee the refurbishment of the rooms within the neoclassical, Grade II-listed building. Rochon's previous work in London includes the refurbishment of the Savoy and the Four Seasons on Park Lane.
Richard Nottage, chairman of the property's owner, St James Hotel Ltd, said: "This package is a great opportunity for the hotel to not only to refinance its debt but also to upgrade its bedrooms, with a bank and team that we know and trust.
"Our hotel has a rich heritage and this new chapter represents an important step to help drive future growth in the competitive central London marketplace."
Paul Smith, corporate development director for Barclays Corporate Banking, Scotland, added: "The competitive package Barclays created for Sofitel London St James showcases our expertise and understanding of the hospitality and leisure sector and our strong track record of funding successful hotel businesses. It also provides the hotel which the opportunity to add to its already impressive facilities and provide guests with an excellent environment from which to explore London.
The hotel's latest financial results', lodged at Companies House, show that the Sofitel London St James achieved a turnover of £22.8m in 2016, as the result of an occupancy of 94% and average daily rate of £297. A 13.8% fall in pre-tax profit year on year to £2.5m was blamed on lower food and beverage revenues.
The Barclays funding deal follows on from subsidiary company St Andrew Square Hotel Ltd, the owner of the Ibis Style St Andrew Square Edinburgh operated by AccorHotels, securing a £5m loan from the bank in 2015.