Envoy Choe Ryong-Hae met Liu Yunshan, a member of the Chinese Communist Party's highest ranking body the Politburo Standing Committee, state television reported on its evening newscast.
China is the North's sole major ally and key economic benefactor. But relations have taken a downturn in recent months in the face of escalating tensions on the Korean peninsula after Pyongyang's nuclear and missile tests, which saw international sanctions tightened.
The report quoted Choe as telling Liu he was sent by Kim to improve, consolidate and further develop relations and that the North was willing to work with China.
Choe also praised China's efforts for peace and stability on the Korean peninsula. He said the North was willing to accept Beijing's proposals to develop dialogue with other parties.
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It was not immediately clear if he was referring to long-stalled efforts -- the so-called six-party talks -- by China, Japan, the United States, Russia and South Korea to persuade the North to abandon its nuclear programme in exchange for aid and security guarantees.
Choe, a vice marshal and director of the Korean People's Army's General Political Bureau, is said to be a close confidant of Kim, who has led North Korea for more than a year.
He is believed to be the highest-ranking North Korean to visit China since Kim's late father and predecessor Kim Jong-Il in August 2011. The elder Kim died in December 2011.
Liu told Choe that China hopes all relevant parties will work for denuclearisation of the Korean peninsula, solve problems through dialogue and achieve an early restart of the six-party talks.
The Politburo Standing Committee has only seven members and is led by President Xi Jinping.