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.