Do, which is run by the copywriter Chris West, has been briefed to produce a poster campaign supporting Selfridges stores in London and Manchester in the run-up to the festive period. The decision comes after a series of presentations from agencies.
West said: "We hope that the appointment will result in an ongoing relationship."
Under its marketing director, James Bidwell, Selfridges has maintained a tradition of avoiding traditional agency routes for its advertising.
Karmarama created its award-winning Tokyo Life campaign with Naked Communications while Dinosaur was briefed to launch its Manchester store.
The Christmas campaign, under the theme "The winter of love", will not focus on specific products but on the Selfridges shopping experience.
Do was set up two years ago by West, whose advertising career spans spells at Saatchi & Saatchi, Bartle Bogle Hegarty, Leagas Delaney and Mother.