PERTH, October 20, 2013 (AFP) - Former leading world amateur Jeong and Fisher finished the tournament locked at 10-under 278 before the Korean claimed victory at the first playoff hole.
Jeong, who carded a closing round of three under 69, held the upper hand when Fisher was left with a four-metre putt for par after fluffing his chip onto the green.
Fisher pushed the putt wide, leaving Jeong with a one-metre putt to win the tournament.
Jeong, ranked 1,066 in the world, sunk the putt to land the title and pocket the US$333,330 winner's cheque.
It also secured him a two-year exemption on the European Tour.
"I was nervous, I was shaking but I controlled myself pretty well all day I thought. Yeah, I don't know what I've done to be honest," Jeong said.
"It means a lot. I was waiting for something like this for a long time. I was going to go back to qualifying school after next week but I guess I don't have to anymore.
"Playing on The European Tour with big name players will be a lot better and a lot more fun."
Overnight leader Australian Brody Ninyette bogeyed two of his final three holes to miss the playoff altogether.
Ninyette finished equal third with Australian Dimitrios Papadatos and England's Danny Willett, while local Brett Rumford finished sixth at seven-under.
Ireland's Peter Lawrie retained his European Tour card after finishing a tie for 18th.
"I'm just glad it's over to be honest with you," Lawrie said. "I've never felt so much pressure than I've felt in the past eight weeks.
"Can't sleep, can't eat properly, it's just horrendous. I wouldn't wish it in my worst enemy.
"Now I'll go home and be with the family and stop being grumpy."
Final round scores at the Perth International at Lake Karrinyup (par-72) in Perth on Sunday (Australian unless stated):
278 - Jin Jeong (KOR) 68-72-69-69, Ross Fisher (ENG) 72-67-71-68 (Jeong won at 1st playoff hole)
280 - Dimitrios Papadatos (AUS) 69-71-72-68, Danny Willett (ENG) 72-71-68-69, Brody Ninyette (AUS) 72-69-67-72
281 - Brett Rumford (AUS) 71-73-65-72
282 - Joel Sjoholm (SWE) 71-73-67-71, Richard Finch (ENG) 72-69-69-72, JB Hansen (DEN) 70-73-66-73.
283 - Peter Hedblom (SWE) 68-69-75-71, Fredrik Andersson Hed (SWE) 69-73-68-73.
284 - Espen Kofstad (NOR) 71-73-72-68, Ryan Haller (AUS) 72-70-74-68, Josh Younger (AUS) 70-70-73-71, Dustin Johnson (USA) 69-74-75-66, Soren Hansen (DEN) 71-69-72-72, James Nitties (AUS) 68-73-69-74.
285 - Daniel Popovic (AUS) 72-74-69-70, Peter Lawrie (IRL) 73-70-72-70, Fabrizio Zanotti (PAR) 75-68-72-70, David McKenzie (AUS) 75-68-71-71, Gareth Paddison (NZL) 74-69-71-71, Marcus Fraser (AUS) 72-70-71-72, Justin Walters (RSA) 76-69-73-67, Oliver Fisher (ENG) 72-72-69-72, Bo Van Pelt (USA) 70-71-71-73, Michael Hoey (NIR) 73-69-69-74.
286 - Craig Lee (SCO) 73-71-72-70, Wade Ormsby (AUS) 73-72-71-70, Alexandre Kaleka (FRA) 74-69-72-71, Nick O'Hern (AUS) 69-73-72-72, Nick Cullen (AUS) 69-73-71-73, Jason Scrivener (AUS) 75-67-68-76.