The brief will combine work previously carried out on individual fruits and integrate them under a single budget and strategy.
PRWeek understands the account is worth 'six figures' and will cover five types of berries.
The work, which aims to make shoppers aware of the work Berry Gardens does with its growers and varieties, will include influencer activity, sampling, social media, events and paid-for advertising support.
The agency is also tasked with helping drive sales, and reports to Berry Gardens commercial director Rob Harrison and communications manager Janine Hatfield.
Harrison said Berry Gardens needed an agency that could work in a fast-paced market.
“There were two big qualities we were looking for in our new agency partner; first was energy and creativity, and Nick and his team blew us away on that front," he said.
“Second was a team that really got the need to take the communication of what we do to the next level, and how agile our comms activity needs to be to support that."
Nick Woods, founder of Sunny Side Up, will lead strategy and creative, while senior account director Dominique Rock will manage the account on a day-to-day basis.
Woods said: “The juice of a strawberry, tang of a Maravilla raspberry, or sweetness of a Victoria blackberry are all ripe for evocative storytelling.
"We need to help turn people on to premium varieties and to really understand the full depth of their amazing health benefits."