The fame gained by his sports winnings led to a career as a martial arts film star, beginning in mainland China and then continuing into Hong Kong. Li acquired his screen name in 1982 in the Philippines when a publicity company thought his real name was too hard to pronounce. They likened his career to an aircraft, which likewise “takes-off” as quickly, so they placed the name Jet Li on the movie posters. Soon everybody was calling him by this new name, which was also based on the nickname, “Jet”, given to him as a young student, due to his speed and grace when training with the Beijing Wushu team. He made his debut with the 1982 film Shaolin Temple. Some of his more famous Chinese films include:

In 1987, Li married Beijing Wushu Team member and Kids from Shaolin co-star Huang Qiuyan, with whom he has two daughters, Si and Taimi. They divorced in 1990. In 1999, Li married Nina Li Chi (born Li Zhi), a Shanghai-born, Hong Kong-based actress. He has two daughters with her, Jane (born 2000) and Jada (born 2002).

Li starred in the 1995 film High Risk, where Li plays a Captain who becomes disillusioned after his wife is murdered by crime lords. Along the way, he pairs up with a wacky sell-out actor, Frankie (played by Jacky Cheung), and proceeds to engage in a series of violent battles in a high-rise building. The setting is similar to that of Die Hard and both their Chinese film titles. This movie is notable in that director Wong Jing had such a terrible experience working with Jackie Chan in Jing’s previous film City Hunter that he chose to make Cheung’s character a biting satire of Chan. Li would later publicly apologise to Chan for taking part in it.

In 1998, he made his American film debut in Lethal Weapon 4 which also marked the first time he had ever played a villain in a film. He agreed to do Lethal Weapon 4 after the producer Joel Silver promised to give him the leading role in his next film, Romeo Must Die (2000), alongside late singer Aaliyah. The film became a box office hit. Though Li spoke very little English at the time of production, his performance as Chinese mafia hitman Wah Sing Ku was praised.

Li turned down Chow Yun-fat’s role in Crouching Tiger, Hidden Dragon (2000) because he promised his wife that he would not make any films during her pregnancy. He also turned down the role of Seraph in The Matrix trilogy, based on his belief that the role was not one which required his skills and that the films were iconic and stunning enough without adding his name to the cast list. Li was also cast as Kato in The Green Hornet when the film was still in development in 2000. In 2001, it was moved to another studio. When the film was moved on again and released in 2011, the role of Kato was portrayed by Jay Chou.

In 2001, he appeared in two more films: The One, which was the first of his films with Jason Statham, and Kiss of the Dragon opposite Bridget Fonda which did moderately well at the box office. In July 2001, Li agreed to produce and star in an action film with Jackie Chan which was to be released in 2002 or 2003, but no further news of their collaboration surfaced until 2006. In 2002, the period martial arts epic film Hero was released in the Chinese market. This film was both a commercial and critical success and became the highest-grossing motion picture in Chinese film history at the time. In 2003 he reunited with producer Joel Silver for the action thriller film Cradle 2 the Grave where he starred alongside rapper DMX and fellow martial artist Mark Dacascos. In 2004, Li lent his likeness, voice and provided motion capture work for the video game Jet Li: Rise to Honor.

Li was presented the Visionary Award by East West Players, the oldest Asian American theatre in the United States, in 2002 by contemporary John Woo. The award recognizes “artists who have raised the visibility of the Asian Pacific American community through theater, film and television.” He delivered his acceptance speech in his native language of Mandarin.

Li took on a more serious role in the 2005 film, Unleashed (a.k.a. Danny the Dog), where he portrayed an adult with the mentality of a child who has been raised like an animal. Although his martial arts skills were used extensively, it was a somber film with more depth than had been previously seen in Li’s films, and co-starred dramatic actors Bob Hoskins and Morgan Freeman.

In 2006, the martial arts film epic Fearless, was released worldwide. Although he will continue to make martial arts films, Fearless is his last wushu epic. In Fearless, he played Huo Yuanjia, the real-life founder of Chin Woo Athletic Association, who reportedly defeated foreign boxers and Japanese martial artists in publicised events at a time when China’s power was seen as eroding. Together with the film Fist of Legend, Li has portrayed both Chen Jun, the student and avenger of Huo Yuanjia (a.k.a. Fok Yun Gap), as well as Huo Yuanjia himself. Fearless was released on 26 January 2006 in Hong Kong, followed by a 22 September 2006 release in the United States where it reached second place in its first weekend.

Li’s 2007 Hollywood film, War, was released in August of that year, and re-teamed him with actor Jason Statham, who previously starred with him in The One, and action choreographer Corey Yuen. War raked in a disappointing US$23 million at the box office, becoming one of Li’s lowest grossers in America; however, it was a hit on video, accumulating nearly US$52 million in rental revenue, more than doubling its box office take. With the exception of Romeo Must Die and the worldwide release of Hero, most of Li’s American/Western films have been only modest hits like Kiss of the Dragon, The One, Unleashed, Cradle 2 the Grave, and the worldwide release of Fearless.

In late 2007, Li returned again to China to participate in the China/Hong Kong co-production of the period war film The Warlords with Andy Lau and Takeshi Kaneshiro. This film, with its focus on dramatics rather than martial arts, netted Li the Hong Kong Film Award for Best Actor.

Li and fellow martial arts veteran Jackie Chan finally appeared together onscreen for the first time in The Forbidden Kingdom, which began filming in May 2007 and was released to critical and commercial success on 18 April 2008. The film was based on the legend of the Monkey King from the Chinese folk novel Journey to the West. Li also starred as the lead villain in the fantasy action film The Mummy: Tomb of the Dragon Emperor with actors Brendan Fraser, Isabella Leong and Michelle Yeoh.

In April 2007, touched by his life-shaking experience in the Maldives when he was close to dying during the 2004 tsunami, Li formed his own non-profit foundation called The One Foundation. The One Foundation supports international disaster relief efforts in conjunction with the Red Cross as well as other efforts, including mental health awareness and suicide prevention. Since the starting of the foundation, Li has been involved with recovery efforts in seven disasters, including the 2008 Sichuan earthquake and Typhoon Morakot in Taiwan. In the 2013 Lushan earthquake in Ya’an, Sichuan, Li and other members of the entertainment sector were the first to appeal for donations of money, goods and materials to help the victims of the disaster. Wu Jing was a One Foundation volunteer and helped in the effort.

In 2009, Li, who previously had US citizenship after years working in the United States, renounced his US citizenship. He was thought to have taken up Singaporean citizenship, although Singaporean authorities did not initially provide any confirmation of this. On 28 July 2009, the chairman of One Foundation (the charity fund of Li) announced that Li had indeed become a Singaporean citizen. He was said to have chosen Singapore for its education system for his two younger daughters.

In 2009, he launched his own fitness program, Wuji. The programme consists of elements of martial arts, yoga and pilates; Adidas launched a special clothing line for it that bears the initials of “JL”.

After a one-year hiatus from filmmaking, Li returned to acting in 2010, portraying a mercenary in the film The Expendables, teaming up with action stars Sylvester Stallone, Jason Statham, Dolph Lundgren, Mickey Rourke, Eric Roberts, Steve Austin, Terry Crews, and Randy Couture. It was the third time he had teamed up with Statham. In 2012, he reprised his role briefly in the sequel The Expendables 2 and returned for the third film The Expendables 3 in 2014. Li was initially stated to be appearing with Vin Diesel in XXX: Return of Xander Cage, but according to a Facebook post by Diesel, Li was replaced by Donnie Yen.

In September 2010, he was appointed by the International Red Cross as the first Good Will Ambassador. He posted online, saying:

It was also announced in September 2010, when Li was attending his wax unveiling ceremony in Hong Kong Madame Tussauds, that Li would be meeting Bill Gates and Warren Buffett to talk about charity work. “Three days ago, I received an email from Gates, hoping I could make time because he and Buffett hoped I could go for a 30-minute chat before the dinner about the future we face as human beings, so I will go,” Li said.

Li had two wuxia feature films released in 2011, The Sorcerer and the White Snake and Flying Swords of Dragon Gate; the latter was helmed by Tsui Hark.

He founded Taiji Zen in 2011, along with co-founder Executive chairman Jack Ma. Taiji Zen is a lifestyle company with the mission of spreading “Health and Happiness for All” through a balance of physical wellness and mental fitness. Taiji Zen combined the martial art of Taijiquan (a.k.a. T’ai Chi Chuan) with mindfulness-based practices such as meditation. It packaged these art forms into several different classes and online programs.

To promote tai chi, in 2012, Li starred in a film titled Tai Chi and co-produced the movie with Chen Kuo-Fu. Li portrayed Tai Chi master Yang Luchan.

In 2013, Li revealed that he suffers from hyperthyroidism and had been dealing with the issue for the past three years. In 2016, he stated that he had recovered from his illness and that accepting fewer film offers was due to his charity work and not because of his health conditions.