Chen Jin skipped the Proton Malaysia Open Super Series and Korea Open Super Series in January. His first tournament in 2009 was the All England Open Super Series. Chen Jin went down 12–21 6–11 (retired) against Lin Dan in the semi-final because of his slightly leg injury. A week later, Chen Jin participated in the Wilson Swiss Open. He was again blown away by Lin Dan, losing 13–21 14–21 in his semi-final match. In May, Chen Jin registered in the Aviva Singapore Open Super Series. He had clashed into the semi-final against his teammate Bao Chunlai. In the semifinal match, he was blown away 19–21 18–21 by Chunlai and have nobond in the final match. A month later, Chen Jin entered the Djarum Indonesia Open. In Indonesia, he has beaten the olympic champion Lin Dan 18–21 21–17 21–4 in the quarters-final. Lin Dan of China may be hurt his somewhere against compatriot Chen Jin. In the semifinal match, Chen Jin was stopped by the world number one Lee Chong Wei with 15–21 20–22. In August, Chen finished second to compatriot Lin Dan 21–18, 21–16 in 45 minutes at the final of 2009 World Championships in Hyderabad, India.
In January, Chen entered the Proton Malaysia Open Super Series. He was clashed into semi-final match in Malaysia against the world number one Lee Chong Wei. Against Lee Chong Wei, he went down in straight games 11–21 13–21. A week later, Chen went to the Korea Open Super Series. He played until the quarter-final match only in the Korea Open. He was again stopped by the 1st seed Lee Chong Wei with rubber games 14–21 21–15 16–21 and ended the tournament. In March, Chen took part in the All England Open Super Series. He lost to Japanese Kenichi Tago with rubber games 20–22 21–19 13–21 in the quarters-final and have no chance for registering in the semi-final. After a week, Chen joined the Wilson Swiss Open. Chen had classed into the final and had won his first champion in 2010. The finalist he beat was his compatriot Chen Long. Chen Jin won in rubber games 12–21 21–15 21–17 in the Swiss Open final. Later in May, Chen represented his country China to play the Thomas Cup Finals 2010 which is held in Kuala Lumpur, Malaysia. Chen and his others men's team members all had clashed into the final match luckily. Chen is ranked no.2 men's singles player of China to play in the Thomas Cup Finals. In the final match, he beat Indonesia's Simon Santoso in rubber games 19–21 21–17 21–7 and had helped all his men's team members won the Thomas Cup's gold medals again. Chinese men's badminton is won 3–0 over the Indonesian team at the Thomas Cup Finals. Three months later, Chen was registering to play the World Badminton Championships in Paris. He was again clashed into the final and won the men's singles gold medal. The finalist played against him in the 2010 World Badminton Championships was the Indonesia's Taufik Hidayat who has outplayed the world number one Lee Chong Wei in the last eight match. He beat Indonesia's Taufik Hidayat 21–13 21–15 in the final competition. In September, Chen Jin joined the China Masters Super Series which is held in his home country. He was outplayed by Chou Tien-chen from Chinese Taipei 18–21 8–16 (retired) in the second round because of his leg injury. After a two-month rest, Chen came back to play in the 2010 Asian Games men's team tournament and the individual tournament which were held in Guangzhou, China. Chen Jin again helped Chinese men's team reach the final by defeating Hong Kong's Chan Yan Kit in the quarter-finals, Indonesia's Simon Santoso in the semi-final and in the final match, he beat South Korean Shon Wan-ho with an easy 21–9 21–15 win. Chen Jin also helped secure the men's team gold medal for China. Later in the individual match, Chen Jin again lost to the world number one Lee Chong Wei in rubber games 21–14 15–21 7–21. Chen Jin was tied at 15–15 in the second game against Lee Chong Wei but let the world number one overtook him in the second game. In the final game, Chen Jin made a lot of careless mistakes and allowed the world number one to pull away at 11–4, 16–6 and 20–7. Hence, Chen Jin could only add a bronze medal for China in the individual event. A week later, Chen took part in the China Open Super Series which was held in Shanghai and reached the semi-finals.