 Jung Sung-ryong made his South Korea U-23 debut, where he kept a clean sheet, in a 1–0 win over Yemen U-23 on 28 February 2007.Later in the year, he kept nine clean sheets in a total, including against Uzbekistan U23 (earning three of the four matches that year), Bahrain U23, and Syria U23.On 27 July 2008, he scored a goal from in the U-23 friendly match against Ivory Coast, setting a Guinness record, which was not broken until Everton keeper Tim Howard scored from in 2012.