[2] He represented his nation South Korea at the 2004 Summer Olympics,[1] and shared silver medals with Park Seon-kwan, Choi Kyu-woong, and Park Tae-hwan in the 4×100 m medley relay at the 2010 Asian Games in Guangzhou, China.

[3][4] Jeong qualified for two swimming events at the 2004 Summer Olympics in Athens, by clearing FINA B-standard entry times of 54.91 (100 m butterfly) and 2:00.84 (200 m butterfly) from the Dong-A Swimming Tournament in Seoul.

[5][6] In the 200 m butterfly, Jeong challenged seven other swimmers on the second heat, including Olympic veteran Vladan Marković of Serbia and Montenegro.

[7][8] In the 100 m butterfly, Jeong blasted a new South Korean record of 54.79 to break a 55-second barrier and top the third heat.

Jeong failed to advance into the semifinals, as he placed thirty-eighth overall out of 59 swimmers in the preliminaries.