The appointment follows a competitive pitch involving four agencies.
The agency will initially be supporting the launch of Mars Bar and Bounty mousses, but there are new products in the pipeline relating to the Milky Way, Galaxy, and Starburst brands.
Joint MD Rita Rowe said the products were aimed at adults and that the challenge was to encourage sampling. The agency will be running promotions and competitions, as well as handling media relations.
Rowe said: 'Everyone knows what Mars tastes like, but there is a thought that a mousse will not be as good as confectionery. We need to persuade them (adults) to try the desserts to find out.'
The account will be run by associate director Sandra McDowell who will report to Eden Vale marketing manager Sarah Lill.