Guo represented China at the 2004 Summer Olympics, earning a gold medal in the 3 metre women's synchronized springboard along with Wu Minxia before finally winning her first individual Olympic gold in the 3 metre women's springboard. She is the leading member of the Chinese national women's diving team after Fu Mingxia. Currently her goal is to win medals at the 2008 Olympic Games in Beijing. She also announced on November 23, 2006 that she would retire following the 2008 Olympic Games.

After the Athens Olympics, Guo gained much fame and was signed up by McDonald's. She was later banned by the national team for excessive commercial activities, but was later taken back.

During a press conference after her performance at the 2008 Diving World Cup in Beijing, China, Guo reportedly was making a bracelet while in conference, and refered the Canadian diver Blythe Hartley as a "fat Canadian". She was heavily criticised in her home country for her mannerless and snubbing behaviour.