Krejcikova is the first Czech to win the title since Hana Mandlikova in 1981Unseeded Czech Barbora Krejcikova sealed her rapid rise in the singles game by claiming a first major title in a hard-fought French Open final.
Krejcikova, 25, won 6-1 2-6 6-4 against Russian 31st seed Anastasia Pavlyuchenkova at Roland Garros.
The former doubles world number one has won the title on her fifth appearance in a Grand Slam singles draw.
On Sunday, Krejcikova has the chance to win the doubles when she plays in the final alongside Katerina Siniakova.
No player has won both the women's singles and doubles titles at Roland Garros since France's Mary Pierce in 2000.
Krejcikova sealed the first half of what could be a rare double when she served out victory with her fourth match point.
When Pavlyuchenkova hit a return long, the Czech clenched her fist in celebration and looked up to the sky as she remembered her mentor Jana Novotna.
"I'm super happy I was able to enjoy it. I'm just really happy," said world number 33 Krejcikova, who has also won two Grand Slams doubles titles.
"It is hard to put into words because I cannot believe what just happened. I cannot believe I actually won a Grand Slam."
'Jana is looking after me from up there' - Krejcikova dedicates win to Novotna
Krejcikova was ranked outside the top 100 last September but is set to rise to 15th in the worldKrejcikova has often spoken about the impact of former Wimbledon champion Novotna, who died in November 2017 from cancer at the age of 49.
When she was 18 and an aspiring player, Krejcikova's parents took her to Novotna's house and asked the former world number two for some advice.
Novotna saw something special and became her coach, mentor and friend until she died.
"I was going through a really hard time when Jana passed away, I was with her most of the time. Her last words were pretty much 'just enjoy it and try to win a Grand Slam'," Krejcikova said.
Pointing to the sky, she added: "I know from somewhere she is looking after me and all this what happened in the last two weeks is pretty much because she is looking after me from up there.
"It is amazing I had the chance to meet her and she was an inspiration. I hope she is really happy and I am extremely happy."
Pavlyuchenkova unable to add senior title to junior success
For the sixth successive year in Paris, there was guaranteed to be a first-time Grand Slam champion crowned in the women's singles final.
Very few - if anyone - would have predicted before the tournament that Krejcikova and Pavlyuchenkova would be the ones contesting it.
That was despite Krejcikova warming up by winning the Strasbourg title and 29-year-old Pavlyuchenkova having reached the Madrid semi-finals last month.
The ability to be mentally strong and bounce back from difficult moments had characterised Krejcikova's run to the final, notably in her semi-final win over Greece's Maria Sakkari.
First she had to save a match point in the deciding set, then was wrongly denied victory by the incorrect overruling of a line call, before composing herself to take her fifth match point moments later.
After two double faults led to her being broken in the first game of the final, Krejcikova responded by rattling off the next six games in just 21 minutes.
The second set was a complete contrast.
Pavyluchenkova, a bigger hitter than the more varied Krejcikova, loosened up and grew in confidence as she started landing more returns on the way to a 5-1 lead.
The Russian lost one of the breaks in the seventh game and then needed a seven-minute medical time-out, where she ate a bag of sweets while receiving treatment, for a thigh injury.
Despite the concerns, she broke in the next game to claim the second set and ensure a decider would determine who won the title.
Breaks of serve were exchanged for 2-2 before Krejcikova regained the initiative with a wonderful returning game where she broke to love.
Pavlyuchenkova, who won two Grand Slam junior titles as a teenager, saved two championship points at 5-3 but could not prevent Krejcikova clinching the title in the next game.
