Mendelsohn, who headed the Speaker Bureau service at Ketchum, will be responsible for PR and social media at mySupermarket and is tasked with raising the profile of the service, which is billed as the third largest supermarket website after Tesco and Asda.
He told PRWeek: "On a b2c level, we’re going to be really focusing on working with journalists so we can support the stories that they’re writing about how to save shoppers money, because we have a huge wealth of data."
Part of the b2b campaign will include working closely with supermarkets and brands to help them develop and market their products more effectively.
"MySupermarket prides itself on being a disruptive force for good and the company is perfectly placed to be the key grocery shopping consumer champion in the UK. I am also excited to be joining at a time when both the cost of living and the supermarket industry are at the forefront of the minds of consumers and the media."
Gilad Simhony, CEO of mySupermarket, said: "MySupermarket has ambitious plans to help all shoppers save the most they can on their grocery shop and we are delighted to have Rafi on board to build on our already impressive growth that we have witnessed over the past few years. Rafi's skills and experience across media relations, social media, b2b and thought leadership will be of great value in enabling us to communicate our brand as the only independent shopping and comparison site."
Mendelsohn has worked for Ketchum’s corporate, tech and public affairs team since early 2010, working on some of the agency's biggest clients including IBM, Nissan and Philips. For the past two years he has headed up the Speaker Bureau service, supporting clients through conference speaker placements.