PrettyGreen won a three-way competitive pitch and will handle WW's press office, provide strategic and creative counsel to the brand, and activate around campaign spikes throughout the year.
The remit includes helping WW, which has recently rebranded, through a brand transition, raising its profile and driving sign ups. PrettyGreen said the account team will operate a reactive newsroom and help amplify the WW ambassador programme.
In their first campaign together, PrettyGreen revealed professional dancer Curtis Pritchard as the latest WW ambassador.
Curtis, who joins the likes of Robbie Williams and Alison Hammond, was recently body-shamed about his weight and has joined WW to "build healthier habits so he can live a more active and healthier lifestyle".
PrettyGreen delivered national coverage for the announcement and said it had exceeded mutually agreed KPIs, securing nearly one million video views across social.
PrettyGreen MD Sarah Henderson said: "We are really excited about what we can deliver working with WW - the brand and the team are a great creative and cultural fit for PrettyGreen and we have a united vision to deliver PR Less Ordinary."
Georgie Carter, head of social, PR and internal comms at WW, added: "PrettyGreen delivered a really strong creative response to brief in the pitch stage – and they’ve gone on to exceed expectations with the results delivered for the Curtis Pritchard announcement, which is testament to the fact that we’ve chosen the right agency."