Ferrer won the all-Spanish match to reach the semifinals without dropping a set.
Robredo got to the quarterfinals by becoming the first man since Henri Cochet at Wimbledon in 1927 to win three straight Grand Slam matches from two sets down. But on Tuesday, he couldn't repeat the feat.
Ferrer will play his second semifinal at Roland Garros against either No. 2 Roger Federer or No. 6 Jo-Wilfried Tsonga. He won seven titles last season, the most for any player on the tour.
A former top-10 player, Robredo missed this tournament the past two years because of a left-leg injury that required surgery.