With Federer, 35, having won this year's Australian Open, this is the first time since 1972 that a man 30 years of age or older has won the first two Slams of a calendar year.
At 31, Nadal might have time to add to his French Open tally.
The pair each pocketed €2.1 million (£1.8 million) for winning from an overall tournament purse of €36 million (£32 million).
Wawrinka is no slouch; he owns three major titles, including one from Roland Garros, and had never lost a Grand Slam final. "This is the most important event in my career".
Rafael Nadal has now won 10 French Open titles, the most titles at a single Grand Slam event of any player in history.
"I feel I was playing well since beginning of the season, but it's true that in my career I have had a lot of good years".
Posting his 15th major victory, and moving into outright second place behind Roger Federer (18) for the most major titles, the Spanish bull completed a phenomenal tournament with a devastating final display.
Past year in Paris, Nadal withdrew before the third round, making the announcement while wearing a blue brace on his left wrist and resignation of his face. He had beaten Nadal in a Grand Slam final before, after all - and the Swiss had just produced his best tennis Friday to beat world No. 1 Andy Murray in the semifinals.
It was the 22nd Slam finale for Nadal; just the fourth for Wawrinka, the oldest man in the championship match in 44 years.
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Wawrinka, who was the 2015 French Open champion, was the picture of grace in defeat.
The Spaniard broke Wawrinka to make it 3-2 and then went on to win the next three games.
An unseeded player has not won the French Open since 1933. "I was trying to play better".
Nadal failed to convert any of the four break points he had in the following game, but drew first blood the next time an opportunity arose to take a 4-2 lead.
- "It's really unbelievable; to win the 10th is incredible, it's very special", the Spaniard said after winning the final.
Rafael Nadal has always been known as the "King of Clay", and no performance exemplified that more than his dominant victory over Stan Wawrinka on Sunday in the French Open final. Not helped by some outrageous stroke making from Nadal, he quickly found himself down 3-0.
Switzerland's Stan Wawrinka misses a return against Spain's Rafael Nadal during their men's final match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Sunday, June 11, 2017. "You were too good".
The Spaniard notched his memorable success on a second match point when three-time Grand Slam victor Wawrinka sent a backhand into the net.