MediaCom picked up the £2 million planning and buying account from the incumbent, Brilliant Media, following a three-way pitch.
Poulter Partners will produce a campaign for the Kumala range, South Africa's fastest-growing wine brand, ranked at fourth by Nielsen Media Research in the UK's top ten wines league table.
Forthcoming activity will look to raise Kumala's profile and reinforce its position against rivals such as Ernst & Julio Gallo and Jacob's Creek.
MediaCom's role extends to providing planning and econometrics in an attempt to make the whole of the Western Wines portfolio more successful. It currently sources about 400 wines from around the world.
In the past year, the distributor has spent about £1 million on above-the-line advertising. The majority of this was concentrated on outdoor, with small amounts of press and radio activity.
David Tobin, the account director at MediaCom, said: "We are looking forward to the challenge of broadening the media channels that wine brands such as Kumala have traditionally used."