Kim Jong-un has become the first North Korean leader to set foot in South Korea by crossing the military line that has divided the peninsula since the end of the Korean War in 1953.
South Korean President Moon Jae-in met Mr Kim at the border at 09:30 (00:30 GMT) before talks begin.
Both men are on their way to the summit venue in the demilitarised zone (DMZ).
The historic meeting will focus on the North’s recent indications it could be willing to give up its nuclear weapons.
In a moment rich with symbolism, Mr Kim and Mr Moon shook hands on both sides of the border in the demilitarised zone.
The South Korean president briefly stepped into the border into North Korea as well – an unexpected moment.
The leaders were met by an honour guard in traditional costume on the South Korean side.
“I am happy to meet you,” Mr Moon told Mr Kim, the AFP news agency reports.
Mr Kim’s recent re-engagement and apparent concessions and have divided analysts, with some questioning the sincerity of his intentions.
Talks are also seen as a prelude to a proposed meeting between Mr Kim and US President Trump by early June, an unprecedented move as no sitting US president has met with North Korean leader.
This is a breaking news story – more to follow.