The account which includes brands such as Cointreau, Mount Gay, The Botanist and Rémy Martin.
Arena Media previously worked with Rémy Cointreau on a consultancy basis but did not handle media planning and buying duties.
The win adds to UM’s portfolio of alcohol brands Fuller’s, Gallo Wines and New Amsterdam Vodka.
Jenia Matthews, marketing manager at Rémy Cointreau UK, said: "We were impressed by UM’s unrivalled experience and passion for our category. Combined with the agency’s steadfast approach to data and creativity, it made them a stand-out partner for us."