Goosen dropped out of a share of the lead with a bogey on the 15th, then slid two back when O'Hern birdied No. 16 for the fourth straight day. Goosen got back within one of O'Hern's lead with a birdie on the par-3 17th.
'It's a great feeling to have a European Tour win under the belt again. It's been a while since I last had a win,' said Goosen, whose last tour victory came at the 2006 South African Airways Open, which was played in December '05.
'Nick played obviously great,' Goosen continued. 'He didn't drive it as well today as he normally does which was surprising. Obviously it never looked like I was going to win. I thought if I could get it to 14 under I could tie him, but instead I hit a great putt on the last.'
O'Hern, who is still looking for his first European Tour crown, posted a 2-under 70 to take second at minus-14. Ernie Els, the 2005 champion, ended alone in third at 13-under-par 275 after closing with a 5-under 67.
Goosen, Richard Green and O'Hern started the final round tied for the lead at minus-12. Green stayed on that number the longest as he parred the first 12 holes in the final round.
Meanwhile, Goosen birdied the first to move to minus-13. O'Hern came right back with a birdie on two, but again fell one behind as he bogeyed the third.
Both Goosen and O'Hern stumbled to bogeys on five. That dropped Goosen into a tie for the lead at 12 under alongside Green.
O'Hern fought back into a share for the top spot with a birdie on nine. He and Goosen matched birdies on 10.
Green fell off the pace with back-to-back bogeys from the 13th. He did recover those strokes with an eagle on 16, but ended bogey-birdie to finish 12 under par.
Goosen and O'Hern parred four straight from the 11th hole to remain tied for the lead and set up the exciting finish.
'After the 15th, I said to my caddie, Colin, you know, we somehow need to get to 15 under,' stated Goosen. 'I hit a good 3-wood on 16 and went for it, but hit a poor chip shot and a poor putt. Then I made two great finishing holes for me. On the 18th, I never hit the fairway once all week and finally I hit a good drive and hit a good 3-wood.'
O'Hern took second place for the seventh time in his tour career.
'Two up with two to play, I thought I was in good shape,' O'Hern admitted. 'I didn't hit the ball well at all, but my short game kept the round going, which is what it's all about. If I had a wedge in my hand at the last, I might have had a chance. I wasn't really expecting him to make eagle, but as they say, expect the unexpected. It's pretty frustrating.'
Graeme McDowell, Stuart Appleby and Green shared fourth place at minus-12. Henrik Stenson, the 2006 winner, tied for seventh with Andres Romero at 11- under-par 277.