Sharapova, ranked second in the world, outplayed Azarenka, who had beaten her in the Australian Open final and the Indian Wells final during her 26-match unbeaten run this year.
This was only a second defeat of the year for Azarenka, who was treated for a wrist injury at the start of the second set.
"In such a tough tournament with difficult opponents, it was a good week," Sharapova said after her first appearance at the indoor event was sealed with the title.
"(Azarenka) was injured today, maybe she could not perform well but I am happy to be the champion here this year."
"I was going to use this event as a warm-up (to the French Open) so I did not come much earlier. Maybe I should continue doing it like that," said the 25-year-old.
Sharapova, far more aggressive in this battle of baseliners, snatched an early break to love and fired two successive aces to take the lead.
The Russian broke her opponent again and fired her fifth ace on set point to rush through the first set in 29 minutes.
Azarenka, who has already won four titles this year, briefly fought back despite the wrist injury but was broken again to trail 5-3.
Sharapova secured the prize money and a luxury sports car with her first match point.
"Obviously I am not happy, but congratulations to Maria," said the 22-year-old Azarenka, who has reached the final in every event she has entered this year. "Still it was a good week for me."