After three years of intensive training with Wu Bin, Li won his first national championship for the Beijing Wushu Team. After retiring from wushu at age 17, he went on to win great acclaim in China as an actor making his debut with the film Shaolin Temple (1982). He went on to star in many critically acclaimed martial arts epic films, most notably the Once Upon A Time In China series, in which he portrayed folk hero Wong Fei-hung.

Li's first role in a Hollywood film was as a villain in Lethal Weapon 4 (1998), but his first Hollywood film leading role was in Romeo Must Die (2000). He has gone on to star in many Hollywood action films, most recently starring beside Jackie Chan in The Forbidden Kingdom (2008), and as the title character villain in The Mummy: Tomb Of The Dragon Emperor (2008) opposite Brendan Fraser. Recently, he appeared in the 2010 film The Expendables.

Li was born Li Lian Jie in Beijing, People's Republic of China. His father died when he was two years old, leaving the family to struggle on its own, with Li being the youngest of two boys and two girls.

Li was eight when his talent for wushu was noticed at a summer course at school, and he began his practice there. Li participated in the sport of wushu in the non-sparring event. He began his wushu on the Beijing Wushu Team, an athletic group organized to perform martial arts forms during the All China Games and his coach was renowned wushu-coach Wu Bin, who did extra efforts to help the talented boy develop, he even brought food for Li's family because they could not afford to buy meat, which was essential for good physical condition of an athlete. As a member of the team, he received wushu training and went on to win fifteen gold medals and one silver medal in Chinese wushu championships, where despite his young age he competed against adults. According to Li, once, as a child, when the Chinese National Wushu Team went to perform for President Richard Nixon in the United States, he was asked by Nixon to be his personal bodyguard. Li replied, "I don't want to protect any individual. When I grow up, I want to defend my one billion Chinese countrymen!" which earned him much respect in his homeland.

Li is a master of several styles of wushu, especially Changquan (Northern Longfist Style) and Fanziquan (Tumbling fist). He has also studied other arts including Baguazhang (Eight trigram palm), Taijiquan (Tai chi), Xingyiquan (Shape intent fist), Zuiquan (Drunken fist), Yingzhaoquan (Eagle claw fist) and Tanglangquan (Praying mantis fist). He did not learn Nanquan (Southern fist), because his training focused only in the Northern Shaolin Styles. He has also studied some of wushu's main weapons, such Sanjiegun (Three section staff), Gun (staff), Dao (Broadsword), Jian (Straight sword) and many more.

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:

Li starred in the 1995 film High Risk, where Jet 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. Jet Li would later publicly apologize 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) which was a box office hit.

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.

In 2001, he appeared in two more Hollywood films: The One 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.