'It was a tussle out there,' said Clark. 'It was a tough day. I struck the ball great all week. Today, under the pressure on the last few holes, to have it come through again, was really great.'
Ian Poulter fired a 6-under 65 to come in alone in fourth place at minus-16.
The beginning of the final round saw a wild flurry of action with Clarke holing out for eagle from the fourth fairway and Angel Cabrera holing out from a bunker for a birdie at the same hole.
Clark birdied the first and third holes to stay on top of the leaderboard, but Lafeber was more spectacular in how he remained in first. He knocked his approaches at the first and second holes inside a foot for tap-in birdies.
Clarke reached the green with his drive at the par-4 ninth and two-putted for birdie to join Clark and Lafeber in the lead at 17-under par. Clark knocked his tee ball to 4 feet at the par-3 eighth and converted the birdie putt to go one ahead at minus-18.
Clarke bogeyed the 11th to fall two back, but Clark would come back to the field. Clark came up short at the 235-yard, par-3 11th and bogeyed the hole.
At the par-3 13th, Clarke reached the green in two and two-putted for a birdie to tie for the lead once again with Clark and Lafeber. Lafeber birdied the 12th to move one ahead, but Clark evened things with a 7-footer for birdie at 13. Lafeber missed a 4-footer for birdie at the same hole so he and Clark were tied at 18-under par.
Lafeber hit a poor approach at the par-4 15th and three-putted for a bogey. He was one down and made par at 16 along with Clark. Clarke was in the clubhouse at 17-under par, so the championship was Clark's to lose.
Clark hit his tee ball at the par-3 17th to the back fringe. Lafeber knocked his to almost the exact same spot, but Clark had the honor and left his birdie try almost 2 feet short. Lafeber's putt grazed the right edge, but did not fall.
At the 18th, both players split the fairway and Lafeber played first. His ball landed 30 feet short of the cup on the right fringe. Clark played his second 15 feet short of the hole.
Lafeber came up short with his birdie putt, but tapped in for par. Clark's putt fell into the center of the cup and that matched Tom Lehman's 1997 tournament record.
'I really did want to make that putt on the last,' admitted Clark, who tied for third at this year's U.S. Open. 'I didn't want to have to make one for par there, so it was great to see that go in.'
Clark collected his third European Tour win and his second this season. He won the South African Open earlier this year and captured the same event three years prior.
Cabrera finished with a 1-under 70 and tied for fifth place with Luke Donald and Nick Dougherty, who both shot rounds of 4-under 67. The group came in at 15-under-par 269.
Miguel Angel Jimenez shot a 3-under 68 and tied for eighth place with Peter Hedblom (67) and Alastair Forsyth (71). The trio was knotted at minus-14.