The South African led after the first and second rounds before Alexander Levy of France and Sweden’s Alex Noren pulled level with Els after Saturday’s third round.
But the four-time Major champion submitted another strong card at the conclusion of a consistent event-wide performance and his 69 was enough to clinch the title with the likes of Levy, Noren and England’s Matthew Baldwin unable to keep up when it mattered most.
"It's great to get my name on this wonderful trophy," Els said. "It's been a while [since I've gone wire-to-wire].
"It's been wonderful, I've had a great week in Germany.
"I've gone a long time trying to win this golf tournament. I really had it going, and then I did make it tough for myself!"
Denmark’s Bjorn continued the recent trend of Els’ partner on the day stepping up their efforts, and after a fantastic 65 round on Saturday shot him into contention, he then matched Els for a 69 card and second place.
"Thomas was playing great until 14, and I was watching the kid [Levy]," Els added.
"He looked like he was staying strong, he has a great game, but he stumbled a bit coming in. I just tried to stay with the basics and it worked."
Levy finished third at 16 under following a closing 71, one shot ahead of Noren, Bernd Wiesberger and Martin Kaymer.
Sergio Garcia crept into the top 10 with a 69 round of his own, completing a strong weekend display having almost failed to make the cut. He was tied for seventh with Wen-yi Huang and Darren Fichardt.
And despite Baldwin falling away with a final-round 74, two Brits hit 69s to finish in the top 10 - John Parry and Paul Waring, They were joined on a total of 13 under by Henrik Stenson and Robert-Jan Derksen.
FINAL LEADERBOARD - TOP 10
270 Ernie Els (South Africa) 63 69 69 69
271 Thomas Bjorn (Denmark) 68 69 65 69
272 Alexander Levy (France) 65 68 68 71
273 Bernd Wiesberger (Austria) 66 68 71 68
- Martin Kaymer (Germany) 64 71 69 69
- Alexander Noren (Sweden) 64 71 66 72
274 Huang Wenyi (China) 71 69 69 65
- Darren Fichardt (South Africa) 70 66 69 69
- Sergio Garcia (Spain) 71 69 65 69
275 Henrik Stenson (Sweden) 68 69 71 67
- Robert-Jan Derksen (Netherlands) 64 72 70 69
- John Parry (Britain) 67 72 67 69
- Paul Waring (Britain) 66 73 67 69
- Sports & Recreation
- Alexander Levy
- Ernie Els