Rajapaksa received Xi and his wife Peng Liyuan at Colombo airport on their arrival from the Maldives.
Xi, also general secretary of the ruling Communist Party, is the first Chinese leader to visit Sri Lanka since 1986.
At least 20 bilateral agreements in the power sector, industry, sea reclamation and water supply and several other areas of engagement running into multi-billion-dollar investments are to be signed during Xi's two-day visit.
Xi will tomorrow launch construction of the port city, which will include the country's first Formula One track.
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Since the advent of Rajapaksa's presidency, China has become Sri Lanka's largest development partner with projects varying from airports, sea ports, road infrastructure and power generation.
China is Sri Lanka's second largest trade partner and second largest source of imports. In 2013, China became Sri Lanka's largest investor and bilateral trade reached USD 3.62 billion.
In addition, the visit will inject fresh vigour into the China-Sri Lanka Free Trade Agreement (FTA) talks. A joint feasibility study completed in March 2014 concluded that signing the FTA will benefit both countries.
Xi's visit to Colombo, the first of its kind since late President Li Xiannian's state visit in 1986, is "important" to the development of bilateral ties, Rajapaksa has said.
Sri Lanka has emerged as a major ally of China in India's backyard. Xi would leave for India tomorrow from Colombo.