Nadal claimed the 62nd title of his career and ensured that he kept up his record of never having lost a match in Brazil - a record he would no doubt love to extend all the way through to the 2016 Olympics, which will also be played in Rio.
Dolgopolov fought bravely and earned three break points in the opening set alone, but Nadal defended them all successfully while also grabbing his only break opportunity to claim the opening set.
The second set saw both players break each other once as it headed to a tie-break, Nadal held firm to clinch the match, and his second title of the year.
"Always when you win a title, it’s special," said Nadal after winning what was the inaugural Rio Open.
" The first edition of a big tournament like Rio, it’s a very important city in the world, and after coming back from injury, it always makes the victory a little more special."
Nadal had saved two match points in his semi-final against Pablo Andujar, and admitted that he'd been relieved to have made it to the final.
"Yesterday was a tough match," said Nadal.
"Pablo played a great match, playing very aggressive. I played too short yesterday and I gave him the chance to have control of the point from inside.
"I’m not very happy with the way I played yesterday, but I think today I was able to play with a little bit more calm, play a little bit longer and go a little bit more for the points. I played a more solid match today."
Dolgopolov, who beat David Ferrer in the semi-finals, was philosophical about not having caught Nadal on an off-day.
"He was playing more solid than I watched him play yesterday," said Dolgopolov.
"The stats were pretty impressive from him. As usual, he was spinning his forehand, making a lot of trouble to hit flat and couldn’t really get used to his serve much - only at the end of the match.
"But I’m quite happy with the week."