The agency has been handed a new brief to handle corporate and consumer work across Itsu's retail and grocery divisions.
Seven Dials’ appointment comes as Itsu begins an aggressive growth programme later this month with the opening of a two-floor shop in Oxford.
The first Itsu outlet outside London, it will be followed by the company opening one new store every month over the next year.
At the same time, the brand will continue to push its grocery range to drive listings in both multiple and convenience retailers.
Earlier this month Bottle was hired to raise the regional profile of Itsu, with a special focus on students.
Simon Kelner, who set up Seven Dials earlier this year, said the aim was "to make the brand as much loved across the UK as it is in the capital".
Itsu was founded in 1997 by Julian Metcalfe, the man behind the global success of Pret a Manger.