[4] Although, Tigran’s father didn't make his sons follow in his footsteps, they received a love of the sport at an early age from him.

[4] After the death of his father, Martirosyan began weight training under the guidance of Ashot Mkhitaryan.

[3] Martirosyan won the silver medal at the 2007 European Weightlifting Championships in Strasbourg, with 331 kg in total.

[5] The next year, he won the gold medal at the 2008 European Weightlifting Championships in Lignano, with 346 kg in total.

[3][6] Martirosyan was initially awarded a bronze medal at the 2008 Summer Olympics, lifting 153 in the snatch, 185 in the clean & jerk and 338 kg in the total.

At the age of 20 years and 64 days, Martirosyan was provisionally recognized as the youngest Olympic medalist from the independent Rupublic of Armenia.

Martirosyan debuted in the middleweight division at the 2009 World Weightlifting Championships in Goyang, where he took second place with a total of 370 kg, losing only to the Chinese weightlifter Lü Xiaojun, who set two of the three middleweight world records at the Championships.

Martirosyan announced before the tournament that he sustained an injured shoulder and, as a result, was unable to compete at full strength.

[17] Martirosyan had the honor of lighting the fire at the Vazgen Sargsyan Republican Stadium in Yerevan for the 5th Pan-Armenian Games on August 13, 2011.