Choi turned pro in 1993 and won the Lineal and WBC light flyweight titles in 1999 with a decision win over Saman Sorjaturong.

[1] He successfully defended the titles three times before losing it to Jorge Arce by a 6th round technical knockout in 2002.

On December 25, 2007, he successfully defended the WBO Intercontinental flyweight title with a unanimous decision victory over Heri Amol.

The scores were Jae Keun Kim 117-110, Dong Ahn Park 118-108, and Muhammad Rois 116-111.

He collapsed while still in the ring after the bout and was rushed to the Soonchunhyang University Hospital immediately after the fight in order to undergo emergency brain surgery.