The campaign is running across outdoor and press, complemented by a loyalty offer which entitles customers to one free cup of Lavazza, a freshly ground coffee, for every three cups bought.
Press ads (below right, click to enlarge) are running across national newspaper titles, including The Sun, today.
The coffee is priced at £1.29 a cup.
The roll-out follows a trial that began in 2009, as KFC moved to change perceptions that it offered chicken-only products.
Coffee has become an increasingly important battleground for fast-food companies out to gain market share.
McDonald's has benefited from selling freshly ground coffee and, in 2010, became the biggest-seller of coffee in the UK, ahead of Costa and Starbucks.
Now KFC is hoping for a similar leap in sales.
Jennelle Tilling, vice-president, marketing, KFC UK, said: "We are very excited to be launching freshly ground, premium coffee across our stores in the UK and are confident it will be a great addition to the menu.
"We're serious about quality and strive to continuously offer the best-tasting products to our customers by using only the finest ingredients and transparently supply chains. Our coffee, as with any other KFC product, will adhere to this ethos."
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