Pavlyuchenkova dropped the first and then battled from behind in each of the next two sets to post a 3-6, 6-2, 6-3 victory over the third-seeded Errani, improving to 6-3 all-time in finals.
The 22-year-old Russian was down 0-3 in the second set, but saved a game point and went on to win the next seven games to take a 1-0 lead in the third.
The Italian then reeled off three straight before Pavlyuchenkova again rallied. She dropped just six points the rest of the way en route to the victory.
Errani, who fell to 7-8 all-time in finals, claimed the runner-up spot in the Paris event for the second straight year after bowing to Mona Barthel in last year's finale.