The Raft, which replaces incumbent agency Designate, will develop and deliver strategic marketing campaigns for Neilson's beach and ski holiday offering, as well as new product launches planned for 2010.
The full service creative agency will handle website design, digital marketing, online display and offline advertising.
Marta Wesolowska, marketing manager at Neilson, said: "We are excited to be working with The Raft. The team impressed us with their strategic thinking, creativity and great understanding of our business."
The Raft, which is based in Cheshire, was founded in 2003 by former BDH\TBWA employees Phil Storton and Shaun Keefe.
Phil Howells, creative director at The Raft, said: "It's a fantastic opportunity to be working with Neilson. We aim to match or better the service reputation they have with their customers, developing campaigns that will position them as the market leader in their field."