Xi and his wife were greeted by South Korean officials at an airport just south of Seoul before heading to their hotel.
Park and Xi were to hold a summit meeting later in the day -- the fifth since they took office in 2013 -- to discuss how to further deepen their relations and how to deal with North Korea's nuclear weapons program, as well as Japan's growing nationalism.
The state visit is widely seen as a snub to North Korea as Xi chose to travel to Seoul first, instead of Pyongyang, a traditional ally of Beijing.
It is the first time for a Chinese president to visit South Korea before traveling to North Korea since 1992 when Seoul and Beijing established diplomatic relations.
Kim Jong-un, who took over North Korea in 2011 after the sudden death of his father and longtime leader Kim Jong-il, has yet to be invited to Beijing.
On Wednesday, North Korea fired two short-range rockets into the sea off its eastern coast, the latest in a series of launches in recent days that could be viewed as its displeasure of Xi's trip to rival South Korea.
South Korea and China have expressed hope that Xi's trip could further strengthen personal ties between the two leaders and enhance their bilateral relations.
Also Thursday, South Korea and China plan to sign a set of agreements that call for, among other things, a strengthened exchange and strategic communication of high-level officials, and facilitation of free trade talks, as well as a launch of a direct transaction market of their currencies, according to South Korean officials.
A won-yuan direct trading market could be helpful for South Korea, whose trade with China makes up more than 20 percent of its total trade, and result in reducing its dependence on the dollar in international trading.
South Korea and its biggest trading partner, China, began negotiations on a free trade agreement in 2012.
"The conclusion of a free trade deal between South Korea and China will further expand economic cooperation and deepen our strategic cooperative partnership," Park said in an interview aired by China's state-run CCTV on Wednesday.
China fought on North Korea's side against South Korea and the U.S.-led U.N. forces in the 1950-53 Korean War, though it has been economically drawn to South Korea in recent decades.
Trade volume between South Korea and China, Asia's fourth-largest and the world's second-largest economies, respectively, stood at US$228.9 billion last year, according to South Korean data.
On Friday, Xi plans to meet with the parliamentary speaker and the prime minister, and deliver a speech to South Korean and Chinese business leaders, and another one to South Korean college students before returning home later that day. (Yonhap)