Cejka, who won in Spain earlier in the year, shot a final-round 70 for a four-round aggregate of 267 to beat Ronan Rafferty, who closed with a 69, Spain's Ignacio Garrido (68) and the Dutchman Rolf Muntz (68) by four shots.
The German's European Tour record 21-under-par aggregate was founded on his first-round 61. He also had the best 36- hole aggregate of 129 and the best 54-hole total of 197.
Cejka, who escaped with his father from Czechoslovakia in 1980 when he was nine and is now a German citizen, said: "I made a bet a few weeks ago with my friend and coach Peter Karz that if I won again this year we would both shave our heads. But I think I will wait until after the Czech Open in Marianske Lazne next week. I was born there and I think people would like to see the real Alexander Cejka.
"I did not say when I would shave my head but I think Peter and I will do it together during the German Open in two weeks' time."
At one stage, he looked like having an unexpectedly close shave yesterday. Garrido, having started six shots behind, closed the gap to one after 11 holes while Rafferty was waiting to pounce only two behind. But Cejka responded to the pressure with birdies at the 12th, 14th and 15th to pull away again.
Rafferty birdied the first, fifth and eighth but he could not hole any more birdie putts in the last 10 holes, despite having several chances.
He did at least have one consolation. He won pounds 18,640 compared to the pounds 8,950 collected by fellow Irishman Paul McGinley, who finished joint fifth on 274 after a last-round 71. That means Rafferty is now less than pounds 37 behind McGinley in the Order of Merit and has improved his chances of earning a place in Ireland's Dunhill Cup team, which will be decided after the Czech Open.Reuse content