The 42,500 sq ft venue, to be called The Twenty Two, will have 31 bedrooms and an all-day restaurant. It will open early next year.
It is the latest move in the reinvention of the square, which was dominated by the Brutalist US embassy, now being converted into the Chancery Rosewood hotel.
The proprietor is hotelier and tech investor Navid Mirtorabi. The interiors are being overseen by the practice of designer Natalia Miyar.
Managing director Darius Namdar said: “We want to break away from how people view members’ clubs in Mayfair and bring together a like-minded community of creative cohorts from all over London, and internationally.
“Our ambition is for The Twenty Two to become London’s ‘living room.’ A place that brings people together who have a common ground, regardless of occupation, age or background.”
The biggest local landlord, the Duke of Westminster’s property company Grosvenor Group, has highlighted its desire to rebrand Mayfair to make it more welcoming for “ordinary” Londoners.