Houston PR, which is based at Somerset House, won the work following a three-way pitch.
The new range, which will be launched in March next year, includes ovens, microwaves, dishwashers, extraction hoods and coffee machines.
The brief includes traditional media relations, with a focus on technology, interiors, cookery and design publications, events and brand partnerships.
Houston managing director Hamish Thompson and associate director James Horne will lead the account and report to Heather Butcher, newly-appointed group marketing manager PR & communications at BSH.
Thompson said: "We’re thrilled to have been appointed to launch these three distinct and prestigious ranges. Domestic cooking is continuing to experience a purple patch in the UK and we’re genuinely excited about the prospect of putting Bosch, Siemens and Neff at the heart of conversations about the way we eat now."