After turning pro at fifteen, Mason and his family moved to Mammoth Lakes, California to pursue his snowboarding career. In 2006, Aguirre became the youngest snowboarder on the U.S. Olympic Snowboarding Team by beating out Ross Powers, 2002 Halfpipe gold medalist and J.J. Thomas, 2002 Halfpipe bronze medalist. Aguirre’s first trip to the Olympics was successful, placing 4th overall in the Halfpipe event which is a major accomplishment considering snowboarding is becoming more and more competitive. Aguirre placed first overall at the 2006 World Superpipe Championships and again at the 2006 Burton New Zealand Open. Known for his aggressive yet smooth riding style, Aguirre regularly pulls off 1080s, 900s and is known for his corkscrewed 540.

Aguirre is a member of the Frends Crew (spelled without the "i" to emphasize the collective nature of the group) made up of snowboarders Kevin Pearce, Danny Davis, Scotty Lago, Keir Dillon, and Jack and Luke Mitrani. Frends is group of riders who turned their initial friendship into a formal alliance in 2007 to move the sport away from its recent competitive and business focus and return the sport to its grass roots, collegial beginnings.