Li started training at the age of eight and he was selected into the national team in 1980. In 1982, he won six of the seven medals awarded at the Sixth World Cup Gymnastic Competition, earning him the title "Prince of Gymnastics" (体操王子/體操王子).
Li is most famous for winning 6 medals at the 1984 Summer Olympics, which was the first Olympics in which the People's Republic of China participated. He won three gold medals (in floor exercise, pommel horse, and rings), two silver medals, and one bronze medal. Li became the most decorated Chinese athlete at the first Olympics that China participated in after the founding of the People's Republic in October 1949.
Li took part in his second 1988 Olympics in Seoul despite carrying injuries. It was an end to an illustrious gymnastic career, as he was off-form and made crucial mistakes which robbed him of the chance of a medal.
Li retired from sporting competition in 1988, and in 1990 he founded Li-Ning Company Limited, which sells footwear and sporting apparel in China. Li remains chairman of the company's board of directors. According to Hurun Report's China Rich List 2014, he has an estimated fortune of RMB 5 billion, making him the 407th wealthiest person in China.