An Jae-sung (born 28 May 1985) is a retired South Korean tennis player.

An has a career high ATP singles ranking of 289 achieved on 14 April 2008.

While a student, he represented South Korea in tennis at the 2006 Asian Games in Doha, Qatar, where he and his teammates won a gold medal in the men's team event, thus securing an exemption from his mandatory military service.

[2][3] An has been a member of the South Korea Davis Cup team from 2005 until 2008, competing in the World Group first round tie in 2008 against Germany.

In 2008, he captured his only ATP Challenger Tour doubles title in Moncton, Canada.