Kim's trip to China - his fourth in the past 10 months - was believed to be an effort to coordinate with his only major ally ahead of a possible second summit with President Trump.
Following their historic meeting in Singapore last June, negotiations have somewhat stalled, as the White House demands that North Korea dismantle its nuclear program first, before the USA would lift any of its punitive measures on the country.
Yonhap said Mr. Kim met with Mr. Xi for about an hour on Tuesday and later attended a dinner at the Great Hall of the People in central Beijing hosted by Mr. Xi and his wife, Peng Liyuan.
For Xi, whose country provides a lifeline to North Korea's anemic economy, the meeting with Kim reminds Trump that China's co-operation will make any nuclear deal more effective. Negotiations have made little headway since.
China and Russian Federation, who both wield vetoes on the United Nations Security Council, have called for easing sanctions to reward Kim's move past year to halt weapons tests and dismantle some testing facilities.
The South Korean president told reporters Thursday that he expected the next summit to produce a "detailed agreement" on disarmament steps by North Korea and corresponding measures by the U.S. He said Kim's trip to China this week was an indication that the North Korean leader was preparing for another tête-à-tête with the U.S. president.
Details of his visit have not been released, but Mr. Kim reportedly met with Chinese President Xi Jinping.
North Korea wants relief from the multiple sets of sanctions imposed on it over its nuclear weapons and ballistic missile programmes, while the USA wants the measures to remain in place until it gives up its arms - something Pyongyang has made no public promise to do.
Relations between China and North Korea had deteriorated in recent years over Pyongyang's nuclear activities, but Mr Kim has made sure to keep Mr Xi informed about his dealings with the USA and South Korea, and ties appear to have warmed.
"If the USA continues to force us unilaterally with sanctions and pressure, we will have no other choice but to seek a different direction".
In an interview with CNBC on Monday, US Secretary of State Mike Pompeo praised China's support for resolving the North Korean crisis and said he did not think the US trade dispute with China would affect this.
The visit coincides with negotiations between USA and Chinese officials in Beijing to resolve a bruising trade war between the world's two biggest economies.
"Their behavior has demonstrated that as well and we appreciate that".
Still, China has denied any interest in using North Korea as a bargaining chip and doing so risked undermining a source of stability in its strained relations with the U.S.
Experts think Kim's China trip was meant to discuss strategies with his closest ally ahead of a possible summit with Trump, adding that it also appears aimed at strengthening the North's negotiating leverage by demonstrating its strong ties with Beijing.
Thus, it's highly likely Kim has pledged to continue exchanges with China in various sectors outside the framework of global sanctions, . while intensifying strategic solidarity with his Chinese counterpart to push the U.S.to offer some form of sanctions relief.