Martirosyan won the World Youth Chess Championship in the Under 16 category in 2016. In 2017 he played for the World team that won the Match of the Millennials in St. Louis, US scoring 4 points from 7 games. In 2018, he won the Armenian Chess Championship and played for the Armenian team in the 43rd Chess Olympiad in Batumi with a performance rating of 2708. Later in the same year, he also won the Zurich Christmas Open edging out Rasmus Svane, SL Narayanan, Dennis Wagner and Andrei Istrățescu. In February 2019, Martirosyan shared first place with Kaido Külaots in the Aeroflot Open, finishing second on tiebreak. Martirosyan entered the Chess World Cup 2021 as the 59th seed. He defeated GM Shakhriyar Mamedyarov in the rapid tiebreaks for round 3, and advanced to round 5 after defeating GM Ante Brkić in round 4. He was eliminated in round five by GM Amin Tabatabaei.