The 20-year-old Ostapenko was the first unseeded woman to lift the Suzanne Lenglen Cup since Britain's Margaret Scriven in 1933.
World number one Serena Williams survived a mid-match meltdown to beat Czech Lucie Safarova 6-3, 6-7(2), 6-2 to win the French Open on Saturday, her 20th Grand Slam singles trophy.
As if playing Novak Djokovic or Andy Murray in the French Open final was not a tough enough task, Stan Wawrinka will probably have to deal with a hostile Roland Garros crowd on Sunday.
Austria's Dominic Thiem strained every sinew trying to cling on to the 32-year-old Spaniard and at times even gained a precarious foothold in his first Grand Slam final. But it ultimately proved a futile mission as, just like in all but two of Nadal's previous 87 matches here, the relentless Spaniard proved insurmountable, winning 6-4, 6-3, 6-2.
For Andy Murray, reaching Sunday's French Open final was a bonus, but he was in no mood to look for silver linings in the aftermath of yet another grand slam reverse at the hands of Novak Djokovic.
Novak Djokovic joined the tennis greats on Sunday when he downed British second seed Andy Murray 3-6 6-1 6-2 6-4 to claim his maiden French Open title and hold all four grand slams at the same time. The world number one recovered from a nervous start to impose his pace on Court Philippe Chatrier and clinch his 12th grand slam crown after three previous failures in a Roland Garros final. Djokovic is only the third man after Don Budge and Rod Laver to hold the four majors at the same time, and the eighth man to triumph at Wimbledon and the French, U.S. and Australian Opens.
IMAGES from matches on Day 9 at the French Open at Roland Garros
No one will be able to match up to his iconic sense of style!
Simona Halep trailed by a set and 5-1 against Elina Svitolina but somehow dug herself out of a hole before storming to victory to set up a semi-final against Karolina Pliskova.
Garbine Muguruza roared into the French Open semi-finals with a 6-2, 6-1 demolition job of Maria Sharapova on Wednesday.
Britain's Andy Murray knocked out defending French Open champion Stan Wawrinka 6-4, 6-2, 4-6, 6-2 in the semi-finals on Friday to reach his first Roland Garros final where he will face world number one Novak Djokovic.
What happened on Day 3 of the French Open was more surprising. Two of the top five seeded women exited.
IMAGES from matches on Day 10 at the French Open at Roland Garros
Sam Stosur powered into the French Open quarter-finals with a 7-6(0), 6-3 win against Simona Halep in Paris on Tuesday, adapting better to damp and heavy conditions than her higher-ranked Romanian opponent.
Round-up of the Rolland Garros tournament being played in Paris.
A summary of Friday play at the French Open.
It's French Open time! The tennis world's only clay court Grand Slam begins on Sunday and the best of the best will battle it out.
Serena Williams did not smile, celebrate or even acknowledge the standing ovation she was receiving from the roaring crowd as she watched Timea Bacsinszky's backhand float out on match point at the French Open on Thursday.
Images from Day 1 of the French Open matches played at Roland Garros on Sunday
A summary of Tuesday's play at the French Open.
Images from Day 9 of the French Open in Paris on Monday.
Images from Wednesday's matches at Roland Garros
Czech fourth seed Tomas Berdych bulldozed his way into the second round of the French Open by thrashing Japanese qualifier Yoshihito Nishioka 6-0, 7-5, 6-3 on Monday.
Claycourt king Rafael Nadal marched into his 10th French Open final after demolishing rising Austrian Dominic Thiem 6-3, 6-4, 6-0, while third seed Stan Wawrinka edged past Andy Murray 6-7, 6-3, 5-7, 7-6, 6-1.
Images from Day 6 of the French Open in Paris on Friday.
Images from Day 6 of the French Open matches played at Roland Garros in Paris on Friday.
Images from Day 3 of the French Open matches played at Roland Garros in Paris on Tuesday
Rafa Nadal got his usual confidence boost from Nicolas Almagro at Roland Garros, reaching the third round with a 6-4, 6-3, 6-1 victory -- his fourth without dropping a set against his Spanish compatriot on the Paris clay.
Photos from French Open matches played at the Roland Garros on Friday
Alize Cornet fought tooth and nail but the local favourite's French Open run came to an end when she was knocked out 6-2, 7-6(9) in the fourth round by Ukrainian 19th seed Elina Svitolina on Sunday.