Chinese Premier Wen Jiabao, South Korean Prime Minister Yoshihiko Noda and Japanese Prime Minister Yoshihiko Noda agreed to meet again in November at the Association of Southeast Asian Nations summit to formalize a free trade agreement, Japan's Kyodo news agency said.
China's Ministry of Commerce said in a statement the agreement was a "milestone" after 13 rounds of talks dating back five years, the state-run Xinhua news agency reported.
In 2011, trade between the three countries was an estimated $690 billion, Xinhua said.
The three countries account for about 20 percent of the world economy, Kyodo said.
The diplomacy and goodwill hit a bump when the South Korean delegation objected to a national gift of crested ibis birds from China alongside the gesture to Japan, the Kyodo agency said.
Both Koreas have disputes with Japan over allegations of World War II female slavery and island sovereignty issues.