The 30-year-old Nadal, who now has 50 clay court titles and 70 in all, will be aiming for a 10th French Open title as well next month.
It was Nadal's first title in almost a year and further cemented his place in history as he became the first man in the Open era to win the same event 10 times.
He won eight Monte Carlo titles in a row from 2005 to 2012 but then lost to Novak Djokovic in the 2013 final.
Nadal's 50 clay titles breaks the record he shared with Guillermo Vilas since April last year when he lifted his ninth trophy in Barcelona.
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"I cannot explain the feelings that I have," Nadal said.
"I had a tough start to the season. When I first played here in 2003 as a qualifier I reached the third round.
"Now, a lot of years later, this is something I could have never dreamt. Thanks to life for giving me this opportunity."
The left-hander now has 29 Masters titles, one behind the all-time record of 30 held by Novak Djokovic.
He has now won an ATP event for the 14th consecutive year after losing his first three finals of 2017.
Nadal was hardly challenged by his 29-year-old countryman, who was playing the best tennis of his career after seeing off world number one Andy Murray on his way to the final.
Nadal took victory as Ramos-Vinolas double-faulted.
"What can you say about Nadal," said the losing finalist.
"Rafa winning here 10 times is unbelievable, he's the best for sure on clay. For me, I still had a fantastic finish to the week."
Nadal will now move on to his home event in Barcelona next week where he will be eyeing another magical 10th title.
Nadal and Ramos-Vinolas played the fourth all-Spanish championship in the Open Era in Monte Carlo, with Nadal winning the 2010 edition against Fernando Verdasco and beating David Ferrer a year later.
Nadal now stand 3-0 versus Ramos-Vinolas and has never lost to a countryman in an ATP final, now standing 15-0 in that category.