Cho said the two sides had exchanged views on the North's denuclearization and on a peace mechanism to replace the armistice that ended fighting during the Korean War.
The meeting Monday at a North Korea-controlled building in the border village of Panmunjom comes amid growing worries about whether North Korea will begin abandoning its nuclear weapons, something officials suggested would happen after Kim's summit with President Donald Trump in June in Singapore.
Kim Jong Un and President Moon held a historic first summit in April in Panmunjom, followed by a second meeting in May, also in the truce village.
The two Koreas held a fresh round of talks at the DMZ today to discuss the third summit, which will be held in September, It was led by the South's Unification Minister Cho Myoung-gyon and Ri Son Gwon, chairman of the North's reunification committee.
At the historic first summit between Moon and the North's leader Kim Jong Un in Panmunjom in April they agreed the South's president would visit Pyongyang during the autumn.
"What's very important is that both governments do all they ought to do regarding progressing all the issues on the agenda", Ri said.
The two sides "agreed at the meeting to hold a South-North summit in Pyongyang in September as planned", the joint statement said, without giving a precise date.More news: PGA Championship showing all but earns Woods Ryder Cup berth
"They are trying to send a message externally that the North-South dialogue momentum has been established and that it will be maintained regardless of the outcome of US-North Korea talks", said analyst Go. "As President Moon stated, "the improvement of relations between North and South Korea can not advance separately from resolving North Korea's nuclear program'".
Pyongyang's denuclearization was discussed by officials setting up the summit on Monday.
North and South Korea agreed on Monday to hold a summit in the North in September, another step towards boosting cooperation between the old rivals, even as doubts grow over efforts to end the North's nuclear weapons program.
Cho, however, said there were no new details on the progress.
The South Korean envoy said he urged Pyongyang to accelerate its current nuclear negotiations with the United States. Analysts say Moon could try to act as a mediator between the U.S. and North Korea, having salvaged the Singapore meeting when Trump abruptly cancelled it.
The North has urged the United States to end the sanctions, saying it had made goodwill gestures, including a moratorium on nuclear and missile tests, the dismantling of a nuclear site, and the return of the remains of some US soldiers killed in the Korean War.
Washington, which cancelled an annual joint military exercise with South Korea that had taken place in August in previous years, has refused to ease sanctions until North Korea finally and fully denuclearizes.