The left-handed Czech 16th seed, who will break into the top 10 for the first time on Monday, overpowered Belarussian Azarenka with some booming groundstrokes to add to her successes in Brisbane and Paris.
The 21-year-old squandered a match point on the Azarenka serve at 5-3 in the second set but made no mistake a game later before raising both arms aloft in triumph.
"I played some of my best tennis today and this has been an amazing tournament for me," she said in a television interview beside the red clay court.
Kvitova, like Azarenka a tall, aggressive player who likes to dominate opponents, made much the faster start on the sun-bathed court and opened a 3-0 lead after breaking her opponent's serve in the second game.
Azarenka claimed a break of her own to get the first set back on serve before Kvitova upped her game to take the tie-break 7-3 and a one-set lead.
She carried her momentum into the second set, breaking again in the opening game but both struggled to hold serve from then on until Kvitova confidently served out for her first win in one of the four premier mandatory events on the WTA Tour.
Azarenka, who won the doubles title with Maria Kirilenko on Saturday, will rise one place above French Open champion Francesca Schiavone to number four when the rankings are updated.
The only left-hander in the top 30 and a semi-finalist at Wimbledon last year, Kvitova will climb to 10th from 18th.
Azarenka, also 21, broke down at the awards ceremony before wishing her opponent luck for the rest of the year.
"I would like to congratulate Petra," she said. "She had a great week and fully deserved to win today."
The next stop on the Tour is in Rome before the French Open gets under way on May 22.
-ReutersTags: sport, tennis, spain