It is the first win for Publicis Chemistry, which officially launched this month, following the acquisition of Chemistry Communications by Publicis earlier this year.
The agency, which won the business after a pitch, will handle all aspects of Gü's digital creative activity, from social media and eCRM to online display advertising and experiential.
Publicis Chemistry is Gü's first dedicated UK digital agency, as the brand looks to ramp-up its activity.
DDB UK, which won the advertising account last year, continues to work with Gü.
Ellie Martin, the marketing director at Gü Puds, said: "The Publicis Chemistry team impressed with compelling digital strategic and creative ideas for Gü, which marry well with our vision and ambitions for the brand."