Following his retirement from boxing, Mayorga decided to properly embark on a professional MMA career and faced Wesley Tiffer on May 3, 2013. He was kept on the ground but able to survive round 1. Tiffer continued to grapple with him on the ground until Mayorga landed a controversial and illegal knee to Tiffer's spine, that of which ultimately heard Tiffer screaming after the blow. Mayorga won via TKO after Tiffer didn't answer the bell for round 3. The Nicaraguan Mixed Martial Arts Commission declared the fight a No Contest for the illegal knee a week later on May 10, 2013 and also suspended Mayorga for 3 months for being 20 pounds over the contracted weight limit of 165-lbs.