It was the second victory of the season for the world's No. 7-ranked player, who won earlier this year in Sydney. Dementieva finished off her 16th professional title in 2 hours, 17 minutes.
"I'm just so happy," said Dementieva, the 2008 Olympic champion. "It was probably one of the most difficult wins in my life."
The 28-year-old Dementieva, who played three consecutive three set matches in Paris, said her pugnacity allowed her to win the title.
"In a match, there is no time to think negative," she said. "You have to fight."
The 46th-ranked Safarova, who played with her right thigh strapped, immediately broke her Russian rival and led 3-0. Dementieva recovered to even the set 3-3 and eventually went to a tiebreaker, where Safarova converted her second set point with a forehand winner down the line.
Dementieva, who lost to Amelie Mauresmo in last year's final, broke in the second game of the second set when Safarova sent a forehand into the net. Dementieva extended her lead to 5-1 when the Czech player missed a forehand after sprinting to the net to retrieve a drop shot and closed out the set on her next service game.
In the final set, Dementieva made the decisive break in the seventh game and clinched victory on her fourth match point when Safarova buried a backhand in the net.