Mario Becerril entered Mexico City’s Military College at the age of 20 and originally signed up to serve as part of an artillery division. When presented with the option to train in either gymnastics or horseback riding in his free time, however, he chose the latter and soon displayed such proficiency that he was eventually transferred to the cavalry. In time, he was selected to represent Mexico in equestrian’s three-day event at the 1950 Central American and Caribbean Games, where he won an individual silver medal. He then competed at the inaugural 1951 Pan American Games and took home a bronze medal from the team event. His final major international tournament was the 1952 Summer Olympics, where he finished 21st out of 59 entrants. He spent his entire career in the military, but was also in charge of the obstacle course for the three-day event when Mexico City hosted the Olympic Games in 1968.