Although the restaurant was initially billed as a project with French chef Jean-François Piège, references to the chef were dropped closer to the time of opening.
Mimosa at the Langham, London has closed after less than six months of trading.
The restaurant replaced Roux at the Landau and was operated by the Paris-based MOMA Group, which also owns Café Lapérouse at Raffles London at the OWO.
After Hot Dinners first reported the closure, a spokesperson for Mimosa confirmed the news and directed those with enquiries to email their bookings team.
The project was first announced in December last year as a partnership between the hotel and chef Jean-François Piège, who is executive chef at the two-Michelin-starred Mimosa in Paris.
However, when the restaurant launched in April as the first outpost of the brand in the UK, references to the chef were dropped and it is understood his affiliation with the project had ended.
The French Riviera-inspired restaurant served Mediterranean dishes such as whole sea bass baked in salt crust with sauce and gratinated taglioni with bechamel, white ham, and Reggiano parmesan.
At the time of the opening, Benjamin Patou, chief executive and founder of MOMA Group, had said: “I am very happy to be opening a restaurant in the Langham.
"I have always loved the hotel and look forward to bringing our finest Riviera cuisine to London with my local partners Khaled Dandachi and Fred Srouchi.”
Earlier this year, the Langham, London, opened Michel Roux’s Chez Roux in the space of Dom Taylor’s Good Front Room.