The agency won the business after a pitch against its rival Unilever roster agency DDB, and will now handle all advertising activity for the brand as it rolls out in various markets over the next 18 months.
Unilever launched Cafe Zero in Italy earlier this year, and is expected to bring the product to the UK and other countries in Western Europe during 2012.
The drink, which Unilever says is aimed at young urbanites, comes packaged in 200ml coffee-style lidded cups, and is available in three flavours: cappuccino, espresso and mocaccino. It will aim to compete with the iced coffee brands, including Starbucks' Frappuccino, that are currently on the market.
DLKW Lowe's appointment further strengthens the agency's global relationship with Unilever. In the UK, the agency works on brands including Knorr, Cif and Domestos, while Lowe Worldwide already works on the Unilever ice-cream brands Magnum and Cornetto.
Unilever currently spends around £5 million to advertise Magnum in the UK, while £2 million is spent on marketing Cornetto.
Tom Knox, the joint chief executive of DLKW Lowe, said: "This is a very exciting assignment for us and a big vote of confidence in our partnership with Unilever."