Cadbury is investing £45m over 10 years in sustainable cocoa
The UK's best-selling chocolate bar is set to become Fairtrade certified, increasing the amount of Fairtrade cocoa sourced from West Africa.
Cadbury's Dairy Milk will make the move - tripling the amount of Fairtrade cocoa sourced from Ghana to about 15,000 tonnes a year - in the summer.
The total annual cocoa production of Ghana is more than 600,000 tonnes.
The Fairtrade mark is designed to secure a better deal for commodity producers in developing countries.
Under the Fairtrade scheme, Cadbury will pay a guaranteed minimum price, even if the open market price falls below it, for Ghanaian cocoa.
However, although the open market price for cocoa has slipped in recent weeks, it still stands above the level guaranteed by the Fairtrade commitment.
The move is part of the Cadbury Cocoa Partnership, a £45m initiative over 10 years designed to help cocoa farming communities across the developing world.
Sales of Fairtrade goods in the UK are increasing dramatically, according to the Fairtrade Foundation.
Since 2001, sales volumes have grown by 40-50% on average, with 1.3 million more households buying Fairtrade goods in 2008 than in 2007, the foundation said.
The value of these goods was £500m in 2007 and £700m in 2008, it added.
And "the recession has not affected purchases of Fairtrade goods - the rate of growth is still increasing," said Harriet Lamb, chief executive of the Fairtrade Foundation.
All own-brand tea and sugar at Sainsbury's, Co-op and Marks & Spencer is Fairtrade, as are all bananas sold at Sainsbury's and Waitrose.
Companies have to pay a minimum price to their suppliers, plus a premium of $150 (£106) a tonne, to qualify for Fairtrade certification.
On top of this, they need to pay a licence fee to the foundation, based on volumes of sales.
These costs are not always passed on to the consumer, said Ms Lamb.