The 331-bedroom hotel, which had been marketed for sale last year, officially joined Autograph Collection this week, less than a month after the luxury, independent collection was launched in the UK with properties in London and Edinburgh.
"This is an incredibly exciting time for the Autograph Collection, and a significant event for us in a prime, central London location," said Amy McPherson, president and managing director for Marriott International in Europe. "Our three Autograph Collection hotels in the United Kingdom offer travellers an enviable range of artistic, culinary and cultural adventures and this historic hotel is a hugely powerful addition."
Accor now has just one venue under its MGallery brand in the UK - the Francis Hotel, Bath.
Speaking to BigHospitality in Bath last year, Jonathan Sheard, who now heads up the MGallery and Mercure teams in Northern Europe, said he hoped the potential sale of St Ermin's would not impact Accor which had identified ten target cities for its upscale concept.