Bjorn, a two-time winner of the event, pulled even with Els at minus-17 with a birdie on No. 18 at Golf Club Gut Larchenhof.
But Els, the wire-to-wire leader, responded with a birdie of his own, finishing up a round of 3-under 69 to end the tournament at 18-under-par 271.
It was the 28th career win on the European Tour for the South African former world No. 1.
Denmark's Bjorn also finished with a 69 Sunday, claiming sole possession of second place at 17-under.
Third place one shot further back went to Alexander Levy (71).