The top seed, who won a seventh straight Monte Carlo Masters crown on his favored clay surface on Sunday, took his phenomenal winning record on the red dust since 2005 to 182-6 to set up a last-16 clash against Colombian Santiago Giraldo.
The Wimbledon, French Open and U.S. Open champion sealed victory on his second match point with a trademark forehand winner down the line that his 60th-ranked opponent was unable to get a racket on.
"I played quite a good match," Nadal said in an interview with Spanish television.
"At times he made more mistakes than probably he usually would and I was able to make the most of that," added the 24-year-old, who missed last year's edition due to injury.
"I am very pleased to be back here in Barcelona after not being able to make it last time."
Third seed Robin Soderling had a day to forget when he was upset 6-2 6-4 by unseeded Croat Ivan Dodig.
The Swede, runner-up at the French Open for the last two years, had his serve broken five times by the 56th-ranked Dodig and misses out on a possible meeting with Nadal in Saturday's semi-finals.
Fourth-seeded Spaniard David Ferrer, beaten by Nadal in the final in Monte Carlo, eased through with a 6-2 6-2 victory over Carlos Berlocq of Argentina.
Unseeded Spaniard Juan Carlos Ferrero beat Germany's Mischa Zverev, who replaced injured second seed Andy Murray, 6-4 7-5.
(Writing by Iain Rogers in Valencia, editing by Tony Jimenez and Pritha Sarkar)