The agency won a four-way pitch for the corporate account and is on a 12-month rolling contract. There was no incumbent in place.
The brief for Hudson Sandler is to liaise with media, business forums, bloggers, analysts and key stakeholders across the UK.
Joules marketing director Ronny Helvey said: "Joules is a dynamic brand that operates as a true multichannel retailer. We have grown to become a £100m turnover business, so we want to ensure our story is noticed and communicated to a wider, discerning audience."
Hudson Sandler managing director Kirsty Leighton said the agency will work on helping Joules to expand globally.