Chef Nuno Mendes is to leave Viajante in the Town Hall hotel, Bethnal Green, in order to become executive chef at André Balazs' new venture, the Chiltern Firehouse.
The Chiltern Firehouse is set to open in London's Marylebone in mid-February.
The Portuguese chef has fronted Viajante in London's Bethnal Green since it opened in 2010 and helped win it the title of best new restaurant in London in the 2011 Harden's restaurant guide. The restaurant has also held a Michelin star since the 2011 guide.
Viajante, which is owned by Singaporean lawyer turned restaurateur/hotelier, Loh Lik Peng, now looks set to close before being replaced by a different venture.
American boutique hotelier Balazs is set to open the Chiltern Firehouse hotel in spring this year, although there are few extra details available.
Mendes is expected to produce a "contemporary, ingredient focused cooking, with underlying American accents", having worked in the USA for 16 years.
He is understood to have been working with Balazs for a year on the new project, and also plans to launch other new restaurants eventually, possibly including a new version of Viajante in a different location.
A statement from Town Hall hotel said: "Town Hall Hotel can confirm that Nuno Mendes will be vacating his post at Viajante to pursue new endeavours. Since Viajante's opening in April 2010, and the successive launch of Corner Room, the hotel has been the recipient of numerous accolades and received mass critical acclaim.
"Moving forward, Viajante Restaurant & Bar will operate as normal until the end of February 2014. Whilst this marks the end of a hugely successful era, Town Hall Hotel wholeheartedly supports Nuno with his new venture and is grateful for putting the hotel on the culinary map of the capital.
"Town Hall Hotel is currently working on a new restaurant concept to replace Viajante that will be announced imminently."