Yao was born to accomplished basketball-playing parents who each stood more than 6 feet (1.8 metres) tall. From an early age Yao towered over his classmates, and by the time he was 12 years old, he was attending a local sports academy and practicing basketball several hours a day. In 1997 he joined the Shanghai Sharks of the China Basketball Association. By the time he led the Chinese team to a respectable 10th-place finish at the 2000 Olympic Games in Sydney, Australia, Yao had become a national icon.

The 7-foot 6-inch (2.29-metre) Yao was drafted by the Houston Rockets with the first overall pick in the 2002 NBA draft. In the 2002–03 season he was voted by fans to start for the Western Conference in the All-Star Game and was a unanimous selection to the league's All-Rookie team. Although the Rockets narrowly missed making the NBA play-offs in 2003, Yao helped lead the team to a 43–39 record—an impressive turnaround from the Rockets' 28–54 record just one season earlier. Yao earned All-Star honours in each of the following four seasons and helped the Rockets to play-off appearances in three of those years (2004, 2005, 2007). In addition to his phenomenal height, Yao was noted for his soft shooting touch and deft passing ability.

Yao's impact on basketball culture extended far past his on-court accomplishments. He drew large crowds wherever the Rockets played, and Houston games were broadcast to huge audiences in China and other Asian countries. A media favourite, Yao became a pitchman for numerous companies and was the focus of the NBA's efforts to popularize the league around the globe.