DURBAN, South Africa, Jan 13, 2013 (AFP) - Oosthuizen entered the final round five shots adrift of leader Scott Jamieson from Scotland, who finished second after a final-hole chip to force a play-off came agonisingly close to dropping.
Former paratrooper Thongchai Jaidee of Thailand ended third a further shot behind, Irishman Padraig Harrington was fourth and Julien Quesne of France and Englishman Danny Willett shared fifth spot.
"What a great week for me and I played really well today," said Oosthuizen after receiving the trophy. "Yesterday was tough as I finished two over, but today was fantastic.
"My third round troubles stemmed from a problem with my swing which I could not fix on the course. I concentrated today on a shorter, tighter swing and it paid off.
"I had a couple of scares during the closing holes -- misreading my par putt at 16 and geting the line completely wrong at 18 to prevent me getting a birdie that would have shut out my rivals."
Oosthuizen posted rounds of 68, 64, 74 and 66 for a 16-under-par total of 272 and succeeded compatriot Branden Grace as winner of the opening European Tour event this year.
It was the sixth success on the European circuit for the 2010 British Open champion and victory in perfect summer conditions lifted him two places to fourth on the world rankings.
The 30-year-old from Mossel Bay in the western Cape birdied four holes on the front nine and another three coming back before dropping a stroke on the par-four 16th, where he misread and pushed a short putt.
Pars at the final two holes seemed to have sealed success in the two million euro ($1.3 million) tournament as Jamieson battled to create final-day birdie opportunities while chasing a second win in Durban within two months.
But the 29-year-old Glasgow-born winner of the Nelson Mandela Championship in the Indian Ocean city during December almost snatched a last-hole eagle with his chipped second shot trickling within millimetres of the pin.
Jamieson started his final 18 holes promisingly with birdies at three and four only to double bogey the par-four fifth and turn in a level 36, leaving him a solitary stroke ahead of Oosthuizen.
After six consecutive second-nine pars, he bogeyed 16, parred 17 and birdied 18 to end with a level-par 72 while Thongchai carded a 68, Harrington a 68, Quesme a 71 and Willett a 68.
Grace, winner of five European titles last season, was always playing catch-up after an opening 75 and although he closed impressively with a five-under 67, ended six strokes behind Oosthuizen.
Scores after final round of the Volvo Golf Champions tournament at par-72, 6,111-metre Durban Country Club Sunday:
272 - Louis Oosthuizen (RSA) 68-64-74-66
273 - Scott Jamieson (SCO) 69-64-68-72
274 - Thongchai Jaidee (THA) 65-68-73-68
276 - Padraig Harrington (IRL) 70-71-67-68
277 - Danny Willett (ENG) 69-70-70-68, Julien Quesne (FRA) 72-67-67-71
278 - Branden Grace (RSA) 75-67-69-67, Paul Lawrie (SCO) 69-70-70-69
279 - Rafa Cabrera-Bella (ESP) 72-69-70-68, Thomas Bjorn (DEN) 69-70-72-68, Nicolas Colsaerts (BEL) 73-67-71-68, Shane Lowry (IRL) 70-69-70-70, Matteo Manassero (ITA) 75-69-66-69, Francesco Molinari (ITA) 70-70-68-71, Richie Ramsay (SCO) 69-73-70-67
280 - Jamie Donaldson (WAL) 69-72-73-66, Jeev Milkha Singh (IND) 69-70-72-69
281 - Paul Casey (ENG) 74-69-69-69, Ernie Els (RSA) 68-72-71-70
282 - Gonzalo Fdez-Castano (ESP) 75-70-69-68, Retief Goosen (RSA) 72-70-70-70
283 - Darren Clarke (NIR) 75-68-71-69, Henrik Stenson (SWE) 72-70-70-71
284 - Robert Rock (ENG) 70-74-70-70
285 - Michael Hoey (NIR) 72-74-66-73
286 - Marcel Siem (GER) 74-74-72-66
288 - Bernd Wiesberger (AUT) 76-71-73-68
289 - Ricardo Santos (POR) 76-76-65-72
290 - Darren Fichardt (RSA) 78-70-75-67, Colin Montgomerie (SCO) 72-78-70-70
292 - Thorbjorn Olesen (DEN) 75-72-74-71
293 - Jbe Kruger (RSA) 75-73-70-75, Jose Maria Olazabal (ESP) 74-72-72-75