Xi will remain in Bangkok, the venue of the regional meeting, until Saturday.
As part of his agenda, he is expected to hold talks with Japanese Prime Minister Fumio Kishida and leaders from other nations.
After participating in the APEC Summit, Xi will develop his State visit to Thailand.
The Chinese head of State arrived in Thailand from Indonesia, where he attended the G-20 Summit in Bali, met with several world leaders, and paid an official visit to that country.
His meeting with Indonesian President Joko Widodo ended with agreements to expand cooperation in the fight against poverty, promote rural revitalization, green development, and the digital economy, and increase investment, among other accords.
Xi is making his second overseas trip this year. His first trip abroad since January 2020 took him to Uzbekistan and Kazakhstan in September.