Upon their initial meeting, Moon and Kim shook hands with the border line between them. Moon then invited Kim to cross into the South, and, after he did so, Kim grasped Moon's hand and led him into the North and then back into the South. They took a ceremonial photo facing the North and then another photo facing the South.
Moon called for more meetings between the leaders and said he wishes to travel in North Korea to visit Mount Paektu near the country's border with China.
Kim told Moon he "won't interrupt your early morning sleep anymore," referring to missile tests, South Korea said.
It was the first time a member of the Kim dynasty was known to set foot on South Korean soil since 1953. The two men shook hands and smiled for news cameras.
The meeting comes weeks before Kim plans to sit down with President Donald Trump. The rogue nation's nuclear capabilities are expected to be a major topic of discussion during the summit with the U.S. leader.
The historic meeting of the two Korean leaders was scheduled down to the last detail. Thousands of journalists were kept in a huge conference center well away from the summit, except for a small group of tightly-controlled pool reporters at the border.
"I feel like I'm firing a flare at the starting line in the moment of (the two Koreas) writing a new history in North-South relations, peace and prosperity," Kim said. Moon responded that there were high expectations that they create an agreement that will be a "big gift to the entire Korean nation and every peace loving person in the world."
Kim and Moon had a full day of talks that are expected to focus on three subjects with worldwide implications -- the denuclearization of the Korean Peninsula, a peace settlement and the improvement of bilateral relations.
The pair ended the first session of talks at about midday local time, with Kim Jong Un returning to the North side of the border to eat lunch, driven in a limousine surrounded by a dozen security guards. Negotiations will resume in the afternoon.