The trip is Xi's first to North Korea in seven years. Ahead of it, he wrote an article in the North Korean Communist Party newspaper Rodong Sinmun, highlighting the "unbeatable" friendship between the countries.
On the ground in Pyongyang, he said he wanted to take the relationship to "new heights."
The two sides should strengthen exchanges in the diplomatic, police and military fields, Xi said.
The two-day visit is widely expected to be aimed at strengthening China's influence over the closed and sanctions-hit neighbor, at a time when Kim has moved closer to Russia. Xi is expected to offer economic aid and - unlike other countries - not press the importance of nuclear disarmament.
