After having his lead cut from four strokes to only one over Angel Cabrera on Saturday, Romero eventually ran out winner by four shots.
A final round 69 - which included an eagle at the 12th - set his winning aggregate at ten under par 274.
It was Romero's sixth title on the Tour de las Americas, where he began his successful international career back in 2003. Since then he has collected victories on the European Challenge Tour, The European Tour and the US PGA Tour.
"I finally won it," said the 28 year old after several close calls over a span of 12 years competing at this event. "I got denied again and again, but now I have won it and I did it playing pretty well. I'm so happy to win at the place I made my debut as a professional back in 1998."
Cabrera, who was denied a record-tying eighth career win at this event for the third consecutive year, ended up posting a one over par 72 to finish as the runner-up.
Trailing Romero by three through 11, Cabrera finally surrendered after a double-bogey on the 12th and a bogey on the 13th.
"I'm very upset because I was fighting hard and the fans were cheering for me. It's quite upsetting to let it go away because of a bad hole," the 2007 US Open Championship and 2009 Masters Tournament champion said about his seven at the par five 12th.