Sharapova -- who is currently No. 2 but will pass Victoria Azarenka for the top spot in the rankings effective Monday -- posted a solid 6-3, 6-3 decision over Kvitova, the world No. 4. It will be her fifth time to reach No. 1, a spot she most recently held June 8, 2008.
Her win came after Errani, the No. 21 seed, upset sixth-seeded Samantha Stosur 7-5, 1-6, 6-3 and collected her first berth in a Grand Slam final.
Saturday's tournament final will be the first career meeting between Sharapova and Errani.
Sharapova has lost just one set in the tournament and took a lead against Kvitova with a break in the fifth game before putting the first set away with a break at love. She got in position to win with a break in the eighth game and sealed the win with her third ace of the day.
Sharapova won 50 percent of the points off Kvitova's serve and finished off four of her six break points while dropping her serve just once.
Errani had a forehand winner for the final point in her semifinal. It was her second win over a Top 10 player in two matches after losing her first 28 matches to highly ranked players. She'd never advanced beyond a Grand Slam quarterfinal before this week.
Stosur was 5-0 lifetime versus Errani and hadn't dropped a set heading into the semifinals but Errani ended the set-win string with a break in the 11th game of the first set and then held for the lead.
Stosur seemed to find her game and went out 5-0 in the second set. But Errani posted an early third-set break and got in position to win for her fourth break of the day that was worth a 5-3 lead.