The agency won the business following a pitch against Enter, Fallon and Havas Worldwide London that was co-ordinated by AAR.
Westons will spend £5m across 2013 to support its range of ciders, which include Stowford Press, Wyld Wood, Old Rosie and Henry Westons.
Ian Lewis, the head of marketing at Westons, said: "We saw four outstanding pitches, but WCRS had the edge with some outstanding strategic thinking and a truly original creative platform."
Matt Edwards, the chief executive of WCRS, said: "Westons Cider has a great story to tell in a fast-growing sector and we’re delighted to be working with them."Follow @Darbs73