Nadal's latest triumph in Paris sees him join Margaret Court, who dominated the Australian Open in the 1960s and 70s, as the only player to win 11 singles titles at one grand slam.
'He had played a great two weeks, ' Nadal said after his 6-4 6-3 6-2 win.
"I am sure", Nadal said after the match, "you will win here in the next couple of years".
Meanwhile, Frenchmen Pierre-Hugues Herbert and Nicolas Mahut won the men's doubles title, while Barbora Krejčiková and Kateřina Siniaková of the Czech Republic claimed the women's doubles title.
Spain's Rafael Nadal poses with ball girls and boys as he celebrates winning the men's final match of the French Open tennis tournament against Austria's Dominic Thiem in three sets 6-4, 6-3, 6-2, at the Roland Garros stadium in Paris, France, Sunday, June 10, 2018.
The Spaniard raced into a 40-0 lead to earn three match points.
Nadal finished another break in the third game to move in front, while injuring his left middle finger midway through the fourth game.
Thiem broke back immediately as he continued to go for his shots, and he saw off a break point to hold for 2-2.More news: Lyon say Nabil Fekir transfer negotiations with Liverpool have ended
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The Spaniard races into a 30-0 lead on his own serve before calling for the trainer mid-game, saying he can not hold his racket.
If there was a scare for Nadal it was an outbreak of cramp in his left hand in the third set, which he managed to shake off, like everything else this fortnight.
Do you think that Nadal can get his record 11th title at Roland Garros or will Thiem be able to pull off something extraordinary? He wound up with 42 unforced errors to Nadal's 24. He also beat the Spaniard in Buenos Aires in 2016.
Nadal, however, turned the screw in the 10th game and Thiem seemed to grow nervous, sending a forehand long to hand his opponent the opening set.
Thiem saved a first breakpoint in that game but couldn't save the second, hitting a forehand wide. Key in that regard was his backhand, which consistently flustered Thiem, who didn't have the same bag of tricks at his disposal.
If Nadal's body can hold up, he still has a chance to make a toss-up of the Federer-vs.
Key statistics: First serve percentage - Nadal 65%, Thiem 45%. The world No 1 lived up to his billing as the heavy favourite with a 6-3 6-3 6-4 victory over surprise finalist Anderson.
Thiem is playing at his limit just to stay in touch. That was part of a five-game run that sent Nadal on his way. Thiem returned to break Nadal's serve in the very next game. The Austrian trails Nadal 2-1. Once again, 18-time Grand Slam victor Martina Navratilova will lend her expertise and insight to ITV's team for the women's final and the team also includes 2013 Wimbledon champion Marion Bartoli, four-time Grand Slam victor Jim Courier, Andy Murray's former coach Mark Petchey, Fabrice Santoro, who played in 70 Grand Slams, and former British ladies number one Samantha Smith.
Nadal enjoyed a fast start to the encounter, winning the opening six points on his way to going 2-0 up in the first set.