The marcoms group is merging its existing fashion agency Relative PR with Paris and London-based MO to create Relative MO.
MO's other existing clients include Giles, Iceberg, Rock & Republic and Giambattista Valli. Relative represents brands including Christopher Kane, Julien Macdonald and Absolut.
Relative senior partner and founder Justine Fairgrieve will head up the agency alongside MO co-founders Mesh Chhiebber and Olivier Bourgis.
The combined agency will maintain offices in London and Paris, with plans to expand in other countries.