The agency was appointed without a pitch as a result of Llewelyn-Bowen and G&R director Jane Reade having worked together previously.
The pair collaborated on unrelated accounts when she worked at Camron PR.
Reade and account director Emma Tweedie head the account, reporting to Llewelyn-Bowen and director of brand sales Suzie Dalton.
'Our primary aim is to raise the awareness of the brand as a mass-market designer name in interiors,' said Tweedie.
She said the brief would see the G&R team co-ordinate with the PR agencies hired by the firms that sell Llewelyn Bowen-branded product lines, such as Graham & Brown, lamps from Turner Lighting and greeting cards firm Hallmark.