The 44-year-old Spaniard, who had a hole-in-one in his round of 68, struck his second shot at No. 18 to within 30 feet and two-putted to claim his 15th tour victory.
Wilson (68) drove into the rough and had to play short of the green. His third shot finished 14 feet from the hole and he two-putted.
"It's my 20th year on tour and so this is a very nice present," Jimenez said. "To win the most important tournament on the European Tour is great."
Jimenez leads the Order of Merit and the European Points List, from which the top five qualify for this year's European Ryder Cup team. He played on winning Ryder Cup teams in 1999 and 2004.
Wilson and Jimenez parred the first playoff hole, also the 18th, after recording 11-under totals of 277.
Jimenez aced No. 5 with a 4-iron, but had a couple setbacks before winning his third event sponsored by BMW. He also captured the BMW Asian Open and the BMW International Open in 2004.
He missed an 18-inch putt on the 15th and muffed a chip from the rough beside the final green on the last regulation hole.
"Now, I cannot say I don't win playoffs anymore," Jimenez said after his first success in three attempts.
The winless Wilson finished second for the fourth time this season and the seventh of his career.
"Second is a good result but I had my chance," he said. "You're not going to get many chances in tournaments like this and I didn't take it."
Robert Karlsson, who lead by four strokes overnight, had a 74 to finish third for the third straight tournament. He needed to make a 5-foot putt for birdie to join the playoff, but three-putted to finish tied with Luke Donald (65) at 279.
"I didn't play well. I never got it going," said Karlsson, who also finished third in the Italian and Irish Opens. "I didn't hole the putts, but it's the best I've ever done around here.
Jyoti Randhawa (70) was a shot further back in fifth, while two-time U.S. Open champion Retief Goosen (66) was tied for sixth at 281 with Andres Romero (67), Alexander Noren (67) and Richard Green (69).
Paul McGinley, the second-round leader with a record 13-under total, had a 72 to finish tied for 10th.