Nadal dominated as beat third-seeded Wawrinka 6-2, 6-3, 6-1 in just over two hours to become the first player to win 10 championships at the same major in the Open era.
Bethanie Mattek-Sands of the United States and Lucie Safarova of the Czech Republic have won their third consecutive Grand Slam title in women's doubles, beating Australians Ashleigh Barty and Casey Dellacqua 6-2, 6-1 in the French Open final.
The Spaniard notched his memorable success on a second match point when three-time Grand Slam victor Wawrinka sent a backhand into the net.
The 32-year-old Swiss had only one break point, early on, and then never threatened Nadal and he blamed himself for being too hesitant.
"He's the best ever on clay; it's always a tough challenge".
An ailing Wawrinka jogged out with a spring in his step following an off-court break, but was back on the ropes after Nadal crunched a forehand victor to his left to break in the opening game of the third set.
The quality of Nadal's flawless tournament adds credence to triple champion Gustavo Kuerten's claim the Mallorcan might eventually win 15 Roland Garros crowns. "It's the most important event in my career without a doubt".
"For sure he's playing the best he's ever played".
"I think from the beginning from my side, for sure, I didn't play my best tennis", Wawrinka said.
Third seed Wawrinka, having beaten world number one Andy Murray with a majestic display of firepower in a gruelling semi-final, arrived full of hope as, at 32, he tried to become the oldest French Open victor since Andres Gimeno in 1972.
His grunts grew louder with every victor, Wawrinka left startled by brutal forehands and backhands that drew gasps from an appreciative crowd who knew they were witnessing something special.
Wawrinka, the French Open champion in 2015 when Nadal lost to Novak Djokovic in the quarter-finals, said the Spaniard had lived up to his expectations on Sunday.
"I was trying to find solution, play better, play the game I wanted to play and do something different", explained Wawrinka.
Nadal said when he first won the title in 2005 he would not have imagined he would still be playing in 2017, let alone winning, and said 10 titles had a special ring to it. "The nerves, the adrenaline, I feel on the court are impossible to compare to another feeling". The sun was shining, there was barely a trace of cloud in the bright blue sky and the temperature was about 85 degrees (30 Celsius).
The crowd got behind the champion of two years ago, but it was only a matter of time before the relentless Nadal put him out of his misery.
Asked if No. 10 was more special than the others, Nadal said yes.
Nadal, 31, this season also posted 10th titles in Monte Carlo and Barcelona and with victory in Paris, he completed the "Triple 10". And I miss playing well at Wimbledon. "So you can never really say you played great against him, for some reason".
And then, in the third, Ostapenko again summoned a veteran's resolve, taking the last five games after being down a break at 3-1.
Nadal forced Wawrinka into another forehand error to break for 2-0 in the second set before the Swiss halted a run of seven games lost with a hold for 1-3.
Key Stat: This was the one that broke Borg's record of six French Open titles. But Nadal pulled away to win four straight games from 2-2.