Pavlyuchenkova captured her first title of the season and her first since winning the Portugal Open in May 2013.
The unseeded Russian dictated the points, making 48 winners to 18 for Errani.
Errani won seven straight games to rally from a 3-1 deficit in the first set and lead 2-0 in the second. But Pavlyuchenkova responded by also winning seven straight games to even the match and lead 1-0 in the third.
In the final set, Pavlyuchenkova hit a backhand return winner to break for a 5-3 lead and sealed the victory with a forehand winner.
Pavlyuchenkova got off to a good start by breaking Errani in the third game. But she made numerous unforced errors to squander that advantage, dropping serve at 3-2 with a wide backhand and at 4-3 with a forehand into the net. Errani hit a backhand drop shot to take the opening set.
Errani broke Pavlyuchenkova in the opening game of the second set with a forehand pass. Pavlyuchenkova saved a break point at 2-0 to stay in the match and the momentum suddenly changed.
Pavlyuchenkova slapped forehand return winners to break serve at 2-1 and 3-2 in the second set before Errani sent a forehand long to lose the set.
In the decider, Errani capitalized on a backhand error from Pavlyuchenkova to break for a 2-1 lead. However, Pavlyuchenkova broke back in the sixth game when Errani's backhand sailed long.
Pavlyuchenkova has defeated three top 10 players in the same tournament for the first time in her career. She beat Maria Sharapova of Russia in the semifinals and Angelique Kerber of Germany in the quarterfinals.
Errani lost in the final of the Paris tournament for the second straight time.