Nadal has now won three Grand Slam titles since turning 30 and only three men, Federer, Rod Laver and Ken Rosewall, who handed over the Coupe des Mousquetaires trophy on Sunday, have managed more, having done it four times.
For the second year running Federer opted against playing at the French Open to spare his knees, but will be favorite to win Wimbledon next month and re-establish a four Grand Slam gap over Nadal on the list of all-time collectors of major titles.
"I had tough moment in the third set with cramps in my hand".
"I had to be very aggressive, he's a very hard opponent", said Nadal.
The duo have met nine times throughout their career, all on clay, with Nadal taking six meetings to Thiem's three.
Nadal is the second tennis player ever to win 11 titles at the same major, since Margaret Court won 11 on home soil at the Australian Open, the last coming near the start of the Open Era in 1973.
With a celebrity audience - including actors Hugh Grant and Tim Roth as well as French stars Marion Cotillard and Jean Dujardin - watching, Nadal flew out of the blocks.
He still occasionally inconvenienced the reigning champion, not least when a deft drop shot brought up a point to break back at 2-4. A spate of poor play quickly saw him lose the first three games of the set.
Ahead of the game, according to ATP, Nadal said that he will have to give his best against a player (Thiem) who is equally great. Thiem stayed with him for the better part of a set, before Nadal pulled away for a 6-4, 6-3, 6-2 victory and his 11th championship at Roland Garros.
That scenario loomed again with Nadal going to 2-0 in the second set on a fifth break point as Thiem fired another backhand wide. It was his best performance of the fortnight, as Nadal confirmed on court, just when he needed it most.
Thiem, mixing heavy topspin and flat groundstrokes and angling balls across the sidelines, saved a break point at 1-2 and two more at 2-3 and there were signs that Nadal was struggling with his timing - over-cooking several forehands.
Bizarrely, Nadal then halted playing in the fourth game complaining of pain in his left hand and stretching his middle finger.
"Typically speaking the trainer and the doctor will come on and make that determination".
Rafael Nadal described his performance at the French Open previous year, when he didn't surrender a set, as "perfect".
He was the first man since Mats Wilander in 1982 to win the French Open on his debut. "You could nearly see the hand start cramping up as the fingers go stiff - it's a awful feeling", Croft said.