The 25-year-old is the first Czech to lift the Suzanne Lenglen Cup since Hana Mandlikova, who represented Czechoslovakia, triumphed in 1981.
Krejcikova won six games in a row to take the opening set after dropping serve in the first, before Pavlyuchenkova gained the upper hand in the second set.
Krejcikova, 25, used her deep ground strokes well to force Cirstea to scramble for returns and combined that strategy with finesse at the net.
"I feel very emotional, really happy. It was an amazing week for me," Krejcikova, who fought back from a set down twice in the tournament to win her matches, said at the trophy presentation ceremony.