Chester Zoo account won by Carat Leeds
Mediacom was the offline incumbent and Code Computerlove previously handled its digital media, with AKA also involved in the pitch.
Jennifer Tegg, marketing manager at Chester Zoo, said: "Carat impressed us with their knowledge and understanding of our sector and brand and we are looking forward to working with them, as an extension of our team, to make our budgets go further."
Opened in 1931, the zoo is one of the UK's largest, spanning 111 acres. It is currently operated by the North of England Zoological Society and claims to be the most-visited wildlife attraction in Britain, with more than one million visitors.
Manchester's Code Computerlove is still involved with the zoo having recently won its £30m (CapEx) Islands project.