Galstyan competed at the 2012 Summer Olympics in the Men's -60 kg division. Galstyan was an underdog and found himself fighting all of the favorites. In the semifinals, he bested Asian Champion Choi Gwang-Hyeon. Galstyan next overcame reigning two-time World Champion Rishod Sobirov, ranked number one by the International Judo Federation, in the semifinals. Finally, Arsen Galstyan and Hiroaki Hiraoka fought in the finals, and Galstyan defeated Hiraoka with an ippon after 41 seconds. Galstyan scored the ippon as he was about to fall victim to an ippon of Hiraoka's. He brought Russia its first gold medal of the Olympic Games. He dedicated his victory to the victims of the flood in the Krasnodar region.