He started his achievements in the international stage by winning the boys' singles title in the Asian and World Junior Championships in 2007, and then won his first professional tournament in the Philippines Open in 2009.

[4] Chen won his first professional title at the Grand Prix Gold event in the 2009 Philippines Open, beating Hu Yun of Hong Kong in the final.

[11] He followed up this disappointment with his best-ever performance in a Super Series event by making it through to the final of the Swiss Open, where he finished runner-up to compatriot Chen Jin.

Chen's first individual title of 2010 came at the Bitburger Open in Germany, where he beat Denmark's Hans-Kristian Vittinghus 21–3, 12–21, 21–9 in the final of the Grand Prix Gold event.

[14] His good form continued when he finished runner-up to teammate Lin Dan at the China Masters two weeks later, going down 15–21, 21–13, 14–21 to the reigning Olympic champion.

[15] Chen obtained a second team gold medal of the year with China at the Asian Games held in Guangzhou, but did not feature in the individual event.

His passage to the final included a controversial walkover by Lin Dan in the quarter-finals and a hard-fought victory over current World champion Chen Jin in the semi-finals.

[17] Chen's attempt at back-to-back Super Series titles came to an end at the hands of former Olympic champion Taufik Hidayat in the semi-final of the Hong Kong Open the following week.

[19] In the first tournament of the new season, Chen Long was convincingly beaten by world number 1 Lee Chong Wei in the semi-final of the Malaysia Open.

[20] The effects of the demoralising defeat were still evident a week later when Chen lost in the second round of the Korea Open to Japanese player Kenichi Tago.

[22] In August, Chen was eliminated in the first round of the World Championships by unheralded Guatemalan player Kevin Cordón in what was one of the shock results of the tournament.

[37][38] After the Olympics, Chen's form picked up tremendously, starting from winning the China Masters in September, where he beat Hong Kong's Hu Yun in the final.

[57] Chen took the blame for the surprise loss of the Chinese Team, casting doubt on his ability to depose Lin Dan as China's MS 'big brother'.

Defeating compatriot Lin Dan in straight sets (21-13, 21-12) en route to the finals, Chen won his second All England title in 3 years with a 15–21, 21–17, 21–15 over Jan O Jorgensen.

[65][66] Chen continued his winning form in his next tournament, the 2015 Malaysia Super Series Premier, defeating Lin Dan, this time with a tighter scoreline of 20–22, 21–13, 21–11.

A second-round exit to Hu Yun at the 2015 Singapore Super Series[68] and a semi-final loss at the Badminton Asia Championships to compatriot Tian Houwei by way of walkover put a stop to Chen's tournament-winning streak.

[70] This was followed by a quarter-finals exit at the 2015 Indonesia Super Series Premier, a tournament in which Chinese players routinely lose during the early stages.

[71] However, Chen would rediscover his form in the 2015 Chinese Taipei Open Grand Prix Gold with a victory over home favorite Chou Tien-chen.

Chen reached the final of the championships with ease, winning in 2 sets over each of his opponents, including Japanese rising star and then-World No.4 Kento Momota 21–9, 21–15 in the semi-finals.

In a rematch of the 2014 final, Chen was again victorious over rival Lee Chong Wei, successfully defending his World Champion title with an easier scoreline of 21–14, 21–17.

[74] In October, Chen continued his fine form by defeating Tommy Sugiarto in the final to win the Denmark Super Series Premier.

After defeating Niluka Karunaratne of Sri Lanka 21–7, 21–10[83] and Poland's Adrian Dziółko 21–12, 21–9[84] during the Group Stage, Chen Long was qualified for the knockout rounds.

[86] Facing Lee Chong Wei in the Badminton Men's Singles final at the Pavilion 4, Riocentro on 20 August 2016, Chen Long clinched the Olympic gold medal after he defeated the Malaysian (Lee Chong Wei) and won the match in straight games with a score of 21–18, 21–18, earning his first Olympic gold medal.

[93] In June, at the Crown Group Australia Open, Chen lost to Kidambi Srikanth in the men's singles final in straight-set game, 20–22, 16–21.

[125] At the delayed 2020 Tokyo Olympics, Chen's first tournament of the year, he managed to reach the final after defeating Raul Must[126] and Pablo Abian[127] in the group stage, Lee Zii Jia in the Round of 16,[128][129] Chou Tien-chen in the quarter-finals[130] and Anthony Ginting in the semi-finals.

Zhang Jun, the President of the Chinese Badminton Association, then revealed that Chen's less-than-ideal performance may have been due to a blister on the ball of his foot that had developed during the group stage of the competition and it was so bad that he could not run.

[136] After not competing on tour since the pandemic-induced postponement of the 2020 Tokyo Olympics, Chen, at the age of 34, officially declared his retirement from professional badminton.

These factors played a significant role in influencing his choice to retire from the national team, marking the end of his illustrious badminton career.

[140] In 2024, Chen was inducted into the Badminton Hall of Fame in the same class as Lee Yong-dae, a former Korean Men's and Mixed Doubles player.

As a result of this, mispronunciation happens a lot, and early in his career when he enrolled in China's athlete system his surname was registered incorrectly as Chen.