In 1975, Choi gained national attention at the Champions Invitational Tournament where he threw a complete game no-hitter against 1974 national champion Kyungbuk High School and took another no-hitter into the ninth inning in the team's next game before it was broken up by an infield single.

Choi took a perfect game with 11 strikeouts into the bottom of the ninth inning against Canada in round-robin phase before giving up a single.

[citation needed] After the impressive performances at the 1981 Intercontinental Cup in Canada, the Toronto Blue Jays showed a strong interest in Choi, regarding him as having the potential to play in the big league immediately.

[1] The Blue Jays' scouts went to see Choi six times before signing him to a major league contract reportedly worth around $250,000.

When the government discovered Choi was heading to Toronto, it threatened to jail the scouts if they tried to leave the country with the contract.

Wearing uniform number 11, Choi hurled 9 complete games and one shutout, and was ranked fourth in ERA and strikeouts.

Choi started for the Giants four times and threw four complete-games with a 3–1 record as a starter, with his final outing being Game 7.

As a clutch "iron arm" pitcher, Choi finished the Series with an astonishing 4–1 record and an ERA of 1.80 in 40 innings pitched in nine days.

[1] Choi became the first member of the 1,000 strikeout club on May 20, 1990 when he fanned Lee Kwang-Eun of the LG Twins in the fifth inning in Daegu.

[9] He was portrayed by Cho Seung-woo in the 2011 film, Perfect Game about the two top pitchers him and his rival Sun Dong-Yeol in the Korea Baseball Organization league during the 1980s.