A joint-forestation project is an effective and feasible means to promote amicable relations between South and North Korea as well as to confer practical benefits onto both parties. During last two decades, the North Korean economy has experienced difficulties, while its forests have rapidly and extensively disappeared and weakened. This paper proposes a joint Korean forestation (JKF) project between the two Koreas to help the desolated North Korean mountains. The UN, the World Bank and other international organizations are eager to confront climate change and help developing countries implement reforestation programs. The UN REDD+ and the World Bank’s FCPF are good financial and technical resources, and the Kyoto Protocol’s CDM provides attractive monetary incentives. South Korea’s growing ODA fund and responsibility also have valuable external effects. Protecting and caring for North Korean forests will essentially be an advance payment in post-unification afforestation as well. A JKF project appears to be the most plausible and cost-effective method in satisfying both Koreas’ political and economic interests.