She took up diving when she was six years old at the Baoding Training Base. She started training in competitive diving in 1988, and was selected to dive for the Chinese national team in 1992. Guo first competed at the Olympics in 1996. Her coach leading up to the 2008 Olympics was Zhong Shaozhen.
During the 2004 Summer Olympics She won a gold medal in the 3 meter women's synchronized springboard along with Wu Minxia, before winning her first individual Olympic gold in the 3 meter women's springboard.
After the 2004 Summer Olympics, Guo became a Chinese national sports figure in the public eye, with a contract with McDonald's, as well as multiple other endorsement contracts. She was later banned by the national team for excessive commercial activities, but was accepted back to the team when she agreed to focus on diving and give up many promotional activities. She was also made to surrender nearly 4 million dollars to the Chinese government, money that she had earned while doing these endorsements. Tian Liang, a fellow Olympic gold medalist offered the same deal as Guo, however declined to pay back the money to the government, and was excluded from the Olympic games. Guo is the leading member of the Chinese national women's diving team, and is known in China as "The Princess of Diving". Guo announced on November 23, 2006, that she would retire following the 2008 Summer Olympics.
Guo won two more gold medals at the 2008 Olympic Games in Beijing. At the end of the Beijing Games, Guo became the most decorated female Olympic diver, and tied fellow Chinese athlete Fu Mingxia, and Americans Pat McCormick and Greg Louganis with the most gold medals (four). Guo won the gold medal in the women's 3-meter springboard with a total of 415.35 points. The silver medal was awarded to Yuliya Pakhalina of Russia, whose score was 398.60, followed by Wu Minxia of China with 389.85 for the bronze medal. In synchronized diving, the defending champions Guo, and Wu, who won the event in the 2004 Athens Olympics and three World Championships, had led the entire competition in Beijing, winning the gold medal, with Yuliya Pakhalina and Anastasia Pozdnyakova of Russia, who posted 323.61, winning Silver.
It was confirmed in January 2011 that Guo has decided to retire, and she will not compete in the 2012 Summer Olympics. She was quoted as saying, "I think I have fulfilled my task, so the London Games is not what I have in mind now. The chances should be left to other talents in the team."
Guo's social activities after the Athens Olympics were the subject of scrutiny in Mainland Chinese and Hong Kong media news outlets. Guo made entertainment headlines in China when the paparazzi published a photograph of her dining with Kenneth Fok Kai-kong, the grandson of the late Hong Kong business tycoon Henry Fok. Guo did not deny the relationship, and has been photographed many times with Kenneth Fok in public. The couple tied the knot in Hong Kong on November 8, 2012.
Guo, along with other divers on her team, suffers from diving-related health problems such as poor eyesight.