The fourth seed, who is also targeting a 10th Roland Garros trophy this year, was always in command as he won his first ATP title since triumphing in Barcelona a year ago.
The 14-times grand slam champion had won his two previous encounters against Ramos and the 15th seed failed to snap that run on Sunday.
"It has been an amazing week on one of the most important events on the tour. I played well here, which helps me a lot to start the claycourt season with confidence," said Nadal.
"For me, that's the most important thing, feel myself happy when I am playing. If I am healthy and I feel myself competitive, I am happy.
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"Then it is obvious I would like to win. But I know if I am in finals of important events, the normal thing is I finally win titles. So today was another chance. I lost the first three finals this year, but with positive feelings. Today I won a very important title for me."
Nadal wasted three break points in the second game as Ramos levelled for 1-1, only for the claycourt king to win the next five games to bag the opening set.
With Nadal's topspin working with devastating effect, Ramos struggled to stay close to his baseline.
The Mallorcan broke for 3-2 in the second set when Ramos sent a backhand long and from then on Nadal was unstoppable.
Ramos ended his first Masters final with a double fault that handed Nadal his 70th ATP title on the third match point.
(Writing by Julien Pretot, editing by Pritha Sarkar and Clare Fallon)
