Nadal, 33, didn’t drop a set all week and improved to 19-2 all-time at this event.
His third Mexican title adds to victories in 2013 and 2005.
“I couldn’t be happier. I played a great event from the beginning to the end,” Nadal said.
“Acapulco was the first big title that I won in my career, so to be able to stay here after 15 years is amazing.
“I can’t thank enough the people who make me feel at home every single time.”
Nadal had never played Fritz before, but it didn’t take him long to figure out the American’s game.
It is the 85th ATP crown for Rafa and the 22nd on hard courts.
Nadal survived 10 aces from Fritz and broke his service three times to outperform the 22-year-old American.
“He’s one of the best players to ever play the game and he showed me why that is tonight,” Fritz said of Nadal.
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