The unseeded 25-year-old defeated Russia’s Anastasia Pavlyuchenkova to claim her first Grand Slam title.
In a match between two first-time slam finalists, it was Krejcikova who came out on top to win 6-1, 2-6, 6-4 on Court Philippe Chatrier on Saturday.
The match ended with Pavlyuchenkova’s backhand landing long on the fourth match point for Krejcikova.
The 25-year-old emulates compatriot Hana Mandlikova who claimed the trophy in Paris in 1981.
Krejčíková paid an emotional tribute to her mentor former Wimbledon champion Jana Novotná who died of cancer at the age of 49 in 2017.
“It’s hard to put into words. I cannot believe I have just won a Grand Slam,” said Krejcikova who was still outside the top 100 when the 2020 French Open, also known as Roland Garros, took place last October.
“I spent a lot of time with Jana before she died. Her last words to me were ‘enjoy tennis and try and win a Grand Slam.’
“I know she’s looking after me. All this is pretty much because she is looking after me.
“It was amazing that I got the chance to meet her. She was such an inspiration. I miss her and I hope she’s really happy.”
Krejčíková, who can also win a third Grand Slam women’s doubles title on Sunday with partner Katerina Siniakova, was presented with the trophy by Czech-born Martina Navratilova who won two French Opens as a United States citizen.
Krejčíková will rise to number 15 in the world as a result of her win on Saturday as she became the sixth successive first-time major victor in Paris.