Wilhem Belocian comes from the French overseas region of Guadeloupe . Since 2011 he has competed internationally for France. In the early days of his career, he participated in a variety of competitions overseas. At the European Youth Olympic Festival in Trabzon, he and his teammates won gold in the relay and silver in the hurdles, winning his first medals in international championships. At the U18 World Championships in Lille he won two bronze medals, again with the relay and in the hurdles. There were also other national youth titles in the hall and in the open air. A year later he competed at the U20 World Championships in Barcelona . There he won bronze again in 13.29 s, which was an improvement of more than two tenths of a second compared to his appearance at the European Championships a year earlier.
In 2013 Belocian won 13.18 s gold over 110 meter hurdles at the U20 European Championships in Rieti . With the relay, he just missed the podium in fourth. A year later he entered the U20 World Championships in Eugene . There he not only won the gold medal in the hurdles, but also set a U20 world record in 12.99 seconds over the 99.0 centimeter high hurdles , which still exists today (as of 2020). He has been competing in the adult sector since 2015. At the European Indoor Championships in Prague he won bronze in 7.52 seconds over the 60 meter hurdles, which is still his best time today. He was also able to win the bronze medal in 13.33 s at the open-air European championships , a year later in Amsterdam. At the highlight of the season, the Olympic Games in Rio de Janeiro , e was disqualified due to a false start in the preliminary run. Shortly afterwards he improved his best time over 110 meter hurdles to 13.25 seconds. The 13.14 s from summer 2019 could not be rated due to a strong tailwind.
Belocian did not compete internationally for the next two years. Not until 2019 did he take part in international championships again with the European Indoor Championships in Glasgow . There he ran over 60 meters hurdles the seventh fastest time in the final. In the summer he won silver in the hurdles sprint at the Universiade . At the World Championships in Doha, he made it to the semi-finals. There he retired with 13.60 seconds as seventh in his run. In 2020 he set a new best time of 13.18 at the Diamond League Meeting in Monaco in August, with which he finished third in the competition.