At the young age of 6 years old, Mark Reyes Jr's father introduced him to the sport of boxing due to his hyperactive behaviour. As Mark grew older he started to realise he had a passion and love for the discipline he was introduced to. He won three national titles in the united states earning him thee gold medal in the national junior Olympics and the crown at 145lbs. Mark was not content. He then decided to fight in Puerto Rico and win two national titles over there too.

His 2016 Olympic dreams were shattered due to an injury he sustained while training so following this in February 2016, he and his father made the metal decision for him to turn professional. His professional debut ended quickly as mark knocked out his opponent within the very first round.