The two-weight world title holder has been out of action since January 2014 due to a contract dispute with ex-promoters Top Rank and made his comeback at the super lightweight limit.
In the first six minutes, and understandably, Garcia was out of sorts but soon found his feet and began teeing off on Rojas to score two knockdowns in the third session.
Much the same happened in the fourth, and as Rojas attempted to fight fire with fire to his detriment, Garcia use pinpoint accuracy and superior power to keep the pressure on.
Midway through the fifth, another barrage put Rojas on the canvas twice and referee Eddie Claudio decided enough was enough to hand Garcia a 35th career victory and a 29th stoppage.
Garcia will attempt to make 135 pounds for a future world title attempt, which would mean the chance to go through a third weight as champion, before possible runs at 140 and 147 pounds later on.
More will become apparent in the coming months, although Garcia may look for a swift return after more than two years in the wilderness with his obvious talent wasted.