Ivory Coast had 16 million hectares of forest in the 1960s.
That figure has fallen to two million hectares, according to official figures, mainly because of the development of cocoa plantations, of which Ivory Coast is the world's main producer, with 40 percent of the market.
Climate change, natural disasters, soil degradation and population movement also contribute to the loss of forest.
The Forests Investment Project aims to cover 6.5 million hectares (16 million acres) -- or 20 percent of the country -- said the World Bank, which is financing the 143-million-euro ($149 million) scheme.
The project would also help preserve 300,000 hectares of forest-land classed as degraded in the southwest, as well as forests in the northern Savanes zone, said Waters and Forests Minister Laurent Tchagba.
The seven-year project will benefit the country's four national parks, including the Tai Forest National Park in the west of the country, classed by UNESCO as a World Heritage Site. It is one of the last remnants of the primary tropical forest of West Africa.
Delegations from other cocoa-producing countries Brazil, Colombia, Ghana and the Dominican Republic all attended the launch of the project.