The top-ranked Spaniard chalked up his 29th straight match at the clay court event when the fourth-seeded Ferrer hit his backhand wide.
It was Nadal's 45th career ATP title and his second consecutive trophy after beating Ferrer at Monte Carlo in straight sets on April 17.
Nadal triumphed at Barcelona from 2005-2009, including finals victories over Ferrer in the 2008 and 2009, before sitting out the last year's edition.
The 24-year-old Nadal became the first player to win two tournaments six or more times_ he has won Monte Carlo seven times_ in the tour's Open era.
Short link: