The victory also allowed the 32-year-old Spaniard to hold onto the No. 1 ranking.
The Coupe des Mousquetaires trophy was back in Nadal's arms after his straight-sets victory over David Ferrer in 2013, but the hard yards were achieved in the semi-finals when he defeated Djokovic 6-4 3-6 6-1 6-7 9-7 in a four-hour, 37-minute epic.
This is Nadal's 17th grand slam title.
After an intense claycourt season in which he also collected an 11th Monte Carlo and Barcelona crown and suffered only one defeat in 27 matches, Nadal will take time out for fishing in his native Mallorca before the grasscourt swing.
"You can win a set, but not a match against Rafa", said Del Potro keen not to over-egg any hint of weakness in Nadal's game.
Rafael Nadal won his 11th French Open title on Sunday.
There is a little advantage Dominic Thiem could take during the French Open final against Rafael Nadal: the weather.
Nadal celebrated in relatively low key fashion, but then there is not much novelty value in this.
Ramos is now in Russian Federation with the Spanish squad as they prepare for the World Cup, but took time out to tweet in Spanish, hailing Nadal for his "dynasty on clay", calling him a "tennis legend" and "sporting hero".
But once a competive first set went the way of the world number one, the plan became damage limitation and Nadal's "undecima" never looked in any doubt.
Thiem found some life and threatened with a break point in the seventh game, but Nadal broke his pace with a drop shot and finished it off with a passing shot, holding for 5-2.
Nadal struck 26 winners to Thiem's 34 yet made only 24 unforced errors to Thiem's 42, with "unforced errors" a relative term in Nadal Roland Garros matches.
Nadal still trails great rival Roger Federer by four major titles although the Swiss star is more than four years older.
"Tough moment", Nadal would say later.
'Of course I would love to have 20 like Roger in the future or even more, but being honest, is something that is not in my mind.
However, in Open Era, he is the first player ever (man or woman) to complete La Undécima in a single Grand Slam event.
Nadal slides across the clay. Like so numerous pretenders, Thiem just did not have quite the same level of consistency to derail the Spaniard, who ruthlessly targeted his flowing backhand. Now, six Slams later, Federer still keeps his lead at three.
Thiem stayed with Nadal in the early going on a cloudy and steamy afternoon; the temperature was 24 degrees Celsius, the humidity approached 70 per cent. When he first halted play, Nadal removed that tape, which he said let his circulation improve.