Vice-President Wang Qishan's trip to South Korea is expected to help Beijing strengthen ties with Seoul as it tries to counter Washington's efforts to step up relations in the region, diplomatic observers said.
Wang, 73, will lead a delegation to attend president-elect Yoon Suk-yeol's inauguration ceremony in Seoul on Tuesday as special envoy of President Xi Jinping, the Chinese foreign ministry said on Friday.
South Korea and China " are important cooperation partners as well as close neighbours", foreign ministry spokesman Zhao Lijian said, announcing the trip.
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Chinese leaders have made few overseas trips since the Covid-19 pandemic erupted in 2020.
The rare trip by a senior leader signals the importance Beijing attaches to relations with Seoul amid tensions with Western countries, particularly the United States, and an economic slowdown at home.
The United States is sending Douglas Emhoff, husband of Vice-President Kamala Harris, as the head of its delegation to the inauguration.
Japanese Foreign Minister Yoshimasa Hayashi will make a two-day trip to Seoul from Monday as Prime Minister Fumio Kishida's special envoy.
US President Joe Biden will visit South Korea after the ceremony and meet Yoon on May 21 before travelling to Japan to meet Kishida.
Biden and Kishida will also meet the Australian and Indian prime ministers at a gathering of the Quad security group.
"Obviously, both China and the US are striving to win over South Korea," said Pang Zhongying, a professor of international relations at the Ocean University of China in Qingdao.
China is watching closely how Yoon will balance his foreign policy priorities of improving its alliance with the US and Japan, while also stabilising relations with China.
"A pro-US president would pose a challenge to China's foreign policy. Wang's trip shows China's strong desire to manage a good relationship with South Korea on fronts from the economy to security," Pang said.
Yoon has taken a harder stance on China than outgoing liberal president Moon Jae-in, who has placed considerable importance on ties with the world's No 2 economy, both in terms of trade and its ability to help negotiate with North Korea.
China is by far South Korea's biggest trading partner, accounting for about a quarter of South Korea's exports last year, helping push bilateral trade to a record US$301.5 billion.