His older brother Mariano Rojas, was a professional cyclist as well, riding for ONCE until 1996.

[4] Rojas was selected to ride the 2012 Tour de France, but crashed out on Stage 3, with a fractured left collarbone, the second retirement of the 2012 Tour after Team Sky's Kanstantsin Sivtsov.

[5][6] Rojas was again selected to ride the 2013 Tour de France and finished 79th overall, one of the highest GC placings among the sprinters; he also finished in 7th place in the points classification with 156 points.

His best result was a third place on the third stage – in which he contested the bunch sprint – which was one of seven top-ten finishes during the Tour.

He was disqualified from the 2014 Tour de France for excessive sheltering behind his team car during the descent of the Tourmalet.