Kim Jong-un has pledged a "new history" in relations with his neighbour as he became the first North Korean leader to set foot in South Korea since the end of the Korean War in 1953.
In a moment rich with symbolism and pomp, South Korean leader Moon Jae-in and Mr Kim shook hands at the border.
Mr Kim said it was the "starting point" for peace, after crossing the military line that divides the peninsula.
It comes just months after warlike rhetoric from North Korea.
Much of what the summit will focus on has been agreed in advance, but many analysts remain sceptical about the North's apparent enthusiasm for engagement.
The meeting - the first between Korean leaders in more than a decade - is seen as a step toward possible peace on the peninsula and marks the first summit of its kind for Mr Kim.
It carries promise for both Koreas with topics being discussed ranging from nuclear technology and sanctions to separated families, and is seen as an opportunity to foster economic co-operation.
"I feel that [we] have fired a flare at the starting point... the moment of writing a new history vis-à-vis peace, prosperity and North-South relations," Mr Kim said ahead of talks with Mr Moon at the Peace House in the border village of Panmunjom.
"A new history begins now," he also wrote in a guestbook.
The White House has expressed hope that the talks will achieve progress towards peace ahead a proposed meeting between Mr Kim and US President Donald Trump in the coming weeks - an unprecedented move.
Talks are likely to focus on reaching an agreement on North Korea's nuclear weapons programme, which has advanced significantly since the last summit more than a decade ago.
Seoul has warned that a deal to rid Pyongyang of its nuclear weapons will be "difficult" to achieve.
Mr Kim announced last week that he was suspending nuclear tests.
The move was welcomed by the US and South Korea, although Chinese researchers have indicated that North Korea's nuclear test site may be unusable after a rock collapse following its last nuclear test.