The second-seeded Russian added the prestigious Paris tournament to her collection of wins that also included the 2008 Australian Open, the 2006 U.S. Open and Wimbledon in 2004.
"It took me many years to get to this stage… . I'm very happy to share it with you," Sharapova, 25, told the appreciative crowd after the match. "No matter how many Grand Slams you win, they are all just as special as the first."
The hard-hitting Sharapova was on her game Saturday, building a 4-0 in the first set and shaking off a broken serve in the fifth game of the second set that kept the 21st-seeded Errani in the match. Sharapova served six aces and hit 37 winners to Errani's 12.
The victory improved Sharapova's record to 18-1 this year, including 16-0 on clay. The win will also move Sharapova into the WTA's world No. 1 ranking next week.