Clijsters was playing her first event since the US Open following a foot injury
Kim Clijsters won the season-ending WTA Championships for the third time with a battling win over world number one Caroline Wozniacki in Doha.
The Belgian, 27, followed up her US Open victory in September by claiming another of the game's premier prizes as she beat Wozniacki 6-3 5-7 6-3.
Clijsters was playing her first tournament since Flushing Meadows because of a foot injury.
Wozniacki had replaced Serena Williams as number one this month.
But without a Grand Slam to her name, the 20-year-old Dane had been hoping to land the biggest title of her career in Doha.
"I'm glad I won and it must be disappointing for Caroline, but I don't know how many more years I'm going to keep doing this," said Clijsters.
This has been a fantastic week for me. Kim just played amazing today and she deserves to win
And the Belgian was supportive of Wozniacki, adding: "She will win a Grand Slam. She is too good of a player not to.
"She's young, she's number, she just has to keep working the way that she has been working. She's been doing really good things, and the good things will keep coming then."
Despite winning six tournaments in 2010, questions will remain over Wozniacki's validity as number one as long as she is without a major, and she is also yet to register a single win over serial Grand Slam winners Clijsters, the Williams sisters or Justine Henin.
Sunday's final provided an opportunity for the Dane to set about rectifying that situation but again Clijsters, who beat Wozniakci in their only previous meeting in the 2009 US Open final, proved the stronger.
Wozniacki had survived a 12-minute opening game in her semi-final win over Vera Zvonareva and she endured a similarly tough start to the final, only this time she buckled.
Clijsters grabbed the break after an eight-minute game and, although Wozniacki levelled for 2-2, it was the Belgian's more attacking game that held sway early on.
Targeting the Dane's less powerful forehand, Clijsters broke again in game five and, despite calling on her father, Piotr, for some advice at a changeover, Wozniacki dropped serve again as the set slipped away.
Clijsters, the champion in 2002 and 2003, grew stronger at the start of the second set and Wozniacki's tenacity was not enough to keep her in touch as the Belgian broke for 3-1.
But with the finish line approaching the world number three showed signs of nerves, a double-fault and a wayward forehand allowing Wozniacki to get the break back and level at 4-4.
Suddenly the top seed had the momentum and, after two break points went begging in game nine, an under-pressure Clijsters gave up the decisive break at 5-5 with a drive-volley into the net and a backhand over the baseline.
After breaks of serve were exchanged at the start of the decider an animated Piotr Wozniacki was back on court to dispense advice to his daughter, but it was Clijsters who took the initiative with some blistering groundstrokes, a forehand winner taking her 4-2 in front.
There was one more twist as Clijsters fell 15-40 down when serving for the match at 5-3, but the US Open champion saved three break points and overcame a double-fault on her first match point to wrap it up when Wozniacki smacked a return into the net.
"I'm kind of relieved because it seemed like it would never end," said Clijsters. "It was just a great battle, great fitness and I think we showed the crowd some great women's tennis."
Wozniacki said: "This has been a fantastic week for me. Kim just played amazing today and she deserves to win.
"In the third set it was very close. She played really well, especially in the important moments. Definitely the experience mattered a little bit today."
In the doubles final, top seeds Gisela Dulko of Argentina and Italy's Flavia Pennetta beat second seeds Kveta Peschke of the Czech Republic and Slovenian Katarina Srebotnik 7-5 6-4.