Kaymer and McDowell both finished in a tie for 13th with 6-under totals of 282, but the Northern Irishman needed to place in the top three to have a chance to overtake the German. His 4-under 68 was not enough, and Kaymer, who finished with a 72, clinched the title while still on the course.
"It's been a fantastic year," Kaymer said. "All of the goals that I set for myself, for my career, everything happened this year. To win the Race to Dubai, No. 1, and to play the Ryder Cup and to win a major."
McDowell said he was happy to have taken the 48-week race for the money title to the wire.
"Things didn't really go my way this week," he said. "It's a golf course which frustrated me last year and continues to frustrate me."
Kaymer's next goal will be to dislodge Lee Westwood atop the world rankings.
"If it happens, it happens," he said. "But if it doesn't happen, I hope that I will have the chance in a few years again."
The 31-year-old McDowell knew he needed an excellent performance to overtake U.S. PGA champion Kaymer. McDowell could have captured the title by winning the tournament or finishing second as long as Kaymer finished no higher than tied for third.
McDowell's season included earning the winning point in the Ryder Cup and the title at the Andalucia Masters. He finished strong in last week's Hong Kong Open, which allowed him to close the gap on Kaymer.
"It's been a dream season," McDowell said. "Just so happened that Martin Kaymer had an unbelievable season as well, and it's just been a great year for European golf and I'm just very proud to be part of that."
Ranked No. 9, McDowell said Westwood's rise to the No. 1 has given him the confidence that he can do it, too.
"Of course, I'd be lying to you if I didn't think I could be the world's No. 1," McDowell said. "I think a few years ago ... Tiger Woods looked pretty untouchable, pretty invincible and we were all playing for second really.
"I think nowadays it's a little different. There's a lot of room for improvement in my game and I know I can continue to get better and better."