London Marriott hired TCG following the agency's work last year on launching its Park Lane hotel.
TCG consumer MD Jon Meakin leads the brief, reporting to Marriott Kensington general manager Ciaran Fahy.
Meakin said work would target both the leisure and corporate sectors: 'The conference and meetings trade market is very important, as these people book way in advance.'
'The sooner we can start raising awareness among this audience the better, but we have found if we position a hotel as a must-stay leisure destination for consumers, it tends to pull in the corporate business as well,' added Meakin.
He leads a team of three, with plans to boost support nearer to the launch date, set for the end of May.
The campaign will culminate in a media reception, attended by key leisure and travel journalists.