After establishing his career on the Korean Tour, where he picked up his first professional win in 1995, and the Japan Golf Tour, where he won twice in 1999, Choi qualified for membership of the U.S.-based PGA Tour by finishing tied 35th at the 1999 qualifying tournament. He was the first Korean to earn a PGA Tour card. In his rookie season in 2000 he finished 134th on the money list and had to requalify, but since 2001 he has been a consistent performer on the tour. In 2002 he became the first Korean to win on the PGA Tour at the Compaq Classic of New Orleans, and followed it up with another victory at the Tampa Bay Classic later that year.