The account was previously held by DDB Media and will transfer to the7stars with immediate effect.
Karl Thomson, managing director at Unique Vacations, the worldwide sales and marketing representatives for the Sandals, Beaches and Grand Pineapple Resorts brands, said: "The7stars has some great credentials in the travel sector, having worked for a number of travel businesses including CityJet. They showed us some creative ideas, all underpinned by an in-depth understanding of the market.
"We're all set for the post-Christmas booking uplift, with some brilliant campaigns planned for the New Year."
In July, Sandals booked a series of strip ads on the front of The Daily Telegraph to advertise its holiday destinations.
Jenny Biggam, founding partner at the7stars, said: "This is a great time to be working for a travel brand such as Sandals. The winter period is a busy time for couples booking romantic breaks, and even weddings and honeymoon packages, and we know we can help Sandals be best placed to grow and increase bookings in the coming busy months, and throughout the year."
Follow Mark Banham on Twitter @Banham72