The win for Els was his third straight at this event and sixth overall, giving him the most wins in tournament history. Els also won the title of this event three straight years from 1994-96.
'It's a great feeling. I see Seve over there and I was lucky enough to beat him on this green in 1994 and that was the best victory of my career,' said Els. 'Some great champions here and to win the title six times is a great feeling.'
Westwood, who moved into the final with a 1-up win over Miguel Angel Jimenez, was in the final of this event for the second time. He won the 2000 title when he beat Colin Montgomerie 1-up in 38 holes.
'It wasn't the best golf you've ever seen, but it was competitive I suppose,' said Westwood. 'I just tried to fight to the end. I probably made too many mistakes on the greens today, and Ernie is a deserving champion.'
Westwood stumbled at the first to a bogey to give Els a quick 1-up lead. However, Els faltered to a bogey at the third and the match was all square.
After the duo halved the fourth with eagles, Els tripped to back-to-back bogeys from the fifth to fall 2-down. The South African fought right back with a birdie on the seventh at the Wentworth Club.
Els, who downed an injured Padraig Harrington 5 and 4 in the semifinal, drained another birdie at the ninth to square the match. Els dropped 1-down again when he bogeyed the 10th, but atoned for that error with an eagle at the 12th to even the match.
Westwood again moved ahead when he dropped in a birdie at the 15th, but stumbled to a bogey at the next to square the match.
The match remained all square into the afternoon 18. Els took the lead for good when he drained a birdie try at the 21st hole. The 2002 British Open champion came right back with an eagle at the next to move 2-up.
Westwood birdied the 23rd hole to get back within 1-down. The pair scrambled to pars at the next four holes. The Englishman missed the green at the 28th hole. He pitched to 9 feet, but missed his par putt to again fall 2-down.
Both men parred the next four holes. Els stumbled to a three-putt bogey at the 33rd. Westwood did the same at the next hole and faced a 2-down deficit with two holes to go.
At the 35th, Els' second shot to the par-5 came up short in the right rough. Westwood, battling a cold that was draining his energy, knocked his second on the green and gave himself a look at eagle.
Els pitched his third to 20 feet. Westwood then rolled his eagle try to tap-in range. Els calmly drained his birdie putt to win the match 2 and 1.
'Well I tell you I got quite fortunate today,' Els said. 'Lee said it earlier, it wasn't the greatest golf, but that is match play. I just tried to stay the course and hit fairways and greens. I couldn't get my iron shots close and Lee hit a great shot in there on 16. I made it difficult for myself, but that's match play.'
'I played pretty good overall,' Westwood said. 'It's a long tiring week and I just ran out of gas there at the end. I haven't felt too good today, but that's part of the game I suppose.'