The Chinese, who started the day with identical points and goal difference to Japan, saw off Hong Kong 2-0 earlier in the day and then waited for the outcome of the last match of the four-nation round robin.
"I think victory in this championship is a chance that Chinese football will change," said China head coach Gao Hongbo. "China are still behind Japan and Korea. [They] have better leagues and are organised better," he said.
"I learned a lot during the tournament, and I think our national team and the youth team can beat them some day. I hope this victory will ignite those people who are working for football," said Gao.
During the game against Hong Kong, Chinese striker Qu Bo opened the scoring against Hong Kong in the 44th minute. A Deng Zhuoxiang corner kick bounced in front of defender Liu Jianye, who sent a floating pass above the Hong Kong defenders to Qu Bo inside the box. The striker then fired a left-footer at close range.
In the 74th minute, substitute midfielder Jiang Ning was sliced down in the area to create a penalty chance, which Qu Bo duly netted for a decisive 2-0 lead.
Korea went on to crush Japan before 42,951 fans who packed the National Stadium in Tokyo. In an exciting match between the two rivals, 20-year-old Korean striker Lee Seung-Yeoul unleashed a 30-metre shot for the go-ahead goal in the 39th minute after the two teams took a goal each on penalties. Midfielder Kim Jae-Sung added another goal in the 70th minute to complete the scoreline.
Brazilian-born defender Marcus Tulio Tanaka received a red card in the 40th minute, while Korean skipper Kim Jung-Woo received a second yellow in the 52nd, forcing the two teams to play with 10-men for the rest of the game.
South Korea coach Huh Jung-Moo said the tournament served as a good test before the World Cup.
"This is a part of preparation for the World Cup," he said. "We lost against China. Perhaps our team was unstable at times. Our ultimate goal is the World Cup, and it was a good experience because we could test what we needed to test and attempt what we needed to attempt."