North and South Korean media outlets confirmed the meeting after South Korean intelligence reported that Kim had visited Beijing with his wife.
Japan's Kyodo News agency had also previously reported that a "special" train from North Korea had crossed the Chinese border into the city of Dandong.
Video footage of a heavily secured train thought to be carrying Kim widely circulated on social media Monday.
According to KCNA, Kim remarked that the meeting with Chinese President Xi Jinping was his "solemn duty."
The visit to China was marked as Kim's first known journey outside the country since he became leader of the DPRK in 2011. The meeting comes ahead of a summit to be had between Kim and US President Donald Trump sometime later this year.
The White House has since confirmed that the meeting did, in fact, take place and that the Chinese government had offered US officials a briefing on the trip.