TH_NK will begin working with Butlins this month and has been tasked with evolving all of its digital channels, including mobile apps, as well as using digital to improve customer's experiences on the resort. It will work with Butlins's brand and design agency, Fitch.
It is understood that the independent digital agency beat Dare, DigitasLBi and The Bio Agency to the business.
Jackie Martin, the sales and marketing director at Butlins, said: "This partnership signals a hugely exciting time for Butlins and digital will play a crucial role in how we evolve our guest experience."
"In TH_NK we have a partner who shares our ambition and vision, with the capability to help us create something really special."
Campaign reported in March that Butlins was looking for an agency to handle digital strategy work.
There was no incumbent on the account and the pitch was overseen by AAR.
Tarek Nseir, the chief executive and founder at TH_NK, said: "Butlins has a place in the hearts of many across the UK, and there is a huge opportunity for digital to play a part in that.
"Together, we will create amazing work that engages with families in fresh and exciting ways. We can’t wait to get started."
In 2012 Butlins appointed Now as its social media agency after a pitch against four other shops. Now won the £5 million Butlins ad account in 2011 and continues to handle both pieces of business.