SEOUL, October 13, 2013 (AFP) - The 26-year-old defeated countryman Kim Tae-Hoon (72) and India's Jyoti Randhawa with a winning total of 12-under-par 276 at the $750,000 competition, now in its third year.
Current Asian Tour number one Kiradech Aphibarnrat of Thailand carded a 73 tie fourth place with Jason Knutzon (69) of the United States and Baek Seuk-Hyun (69) of Korea.
Kang was in imperious form, shooting four straight birdies starting from the third hole. He bogeyed holes eight and 16 but was still comfortably in charge.
He is the only other player apart from K.J. Choi to win the CJ Invitational which has been staged on the Asian Tour Schedule since 2011.
Choi, who won the event in 2011 and 2012, shot a 73 to finish to finish a disappointing tied 21st.
"It feels like I'm dreaming. I can't believe that I won. Maybe I'll wake up tomorrow and the winning feeling will sink in," said Kang according to a statement released by organisers.
"To be honest I felt very comfortable after nine holes. I was looking at the scores and I saw that I had a big lead so I was able to play it safe and try to give myself chances.
"It has been quite a while since I last won so this is a great feeling," he added.
Choi, who had hopes of becoming the first player to win the same Asian Tour event three times in a row, said he welcomed the emergence of a new champion.
"I'm very pleased with the way the young players are playing. If more young players play well then it will boost the stature of this event as well as the golf industry in Asia.
"It has been a very good week and I'm proud to see a new champion win my event," said Choi.
Scores after round 4 of the CJ Invitational Hosted By KJ Choi being played at the par 72, 7226 Yards Haesley Nine Bridges GC course
276 - Kang Sung-Hoon (KOR) 68-69-69-70.
281 - Jyoti Randhawa (IND) 67-74-73-67, Kim Tae-Hoon (KOR) 66-69-74-72.
282 - Jason Knutzon (USA) 72-71-70-69, Baek Seuk-Hyun (KOR) 70-73-70-69, Kiradech Aphibarnrat (THA) 66-71-72-73.
283 - Kim Gi-Whan (KOR) 69-72-72-70, Maeng Dong-Seop (KOR) 69-70-70-74.
284 - Panuphol Pittayarat (THA) 70-77-69-68, Zaw Moe (MYN) 70-74-71-69.