St Luke's has been appointed by luxury desserts brand Gü as its creative agency, following a remotely held pitch against Uncommon Creative Studio, Isobel and Lucky Generals.
St Luke's appointment comes as the brand plans to increase its marketing investment and bolster brand awareness and take-up.
The agency becomes responsible for developing a new brand platform and creating campaigns underlining Gü's distinctiveness in the dessert market.
The shortlist was drawn up by The Observatory International, and the review was handled by Gü's marketing department, led by Amy Heap.
It is understood that Gü previously worked with several agencies on a project basis, and that St Luke's is the first agency in recent years to have been retained.
Gü was founded in 2003 to offer consumers premium, restaurant-quality, often chocolate-based desserts, which are packaged in distinctive glass ramekins. The range includes puddings, mousses and free-from and lower-calorie variants.
Neil Henderson, St Luke's chief executive, said: "It's rare to see a brand with such a passionate and engaged fan base, and we are delighted to be asked to translate that passion into a delicious brand idea for a new generation of dessert lovers."
Richard Denney, the agency's executive creative director, added: "I can't wait to get stuck in, not only to help them drive their business forward but also indulge in their entire range of desserts."
Heap added: "The next couple of years will see a step change in our brand communications and investment, and St Luke's will form an integral part of bringing this to life for our consumers."
Previous work for the brand includes Adam & Eve/DDB's "Give in to Gü" from 2013.