Mohamed Nasir Abbas gained his first experience in international championships at the Arab Youth Championships 2013 in Cairo , where he won the gold medal over 400 meters and with the Qatari sprint relay (1000 meters). He then took part in the youth world championships in Donetsk , where he finished sixth over 400 meters and fourth in the sprint relay. In 2014 he won the gold medal in the 400-meter run and bronze in the 4-by-400-meter relay at the Junior Asian Championships in Taipei . He then took part over 400 meters in the Junior World Championships in Eugene , but was disqualified there in the preliminary run. At the Asian Games in Incheon , South Korea , he was eliminated in the first round. Two years later he won the gold medals at the Asian Indoor Championships in Doha with the Qatari 4 x 400 meter relay and took fourth place in the individual competition. In 2017 he competed at the Asian Championships in Bhubaneswar over 800 meters and reached fourth place. At the beginning of September he won the silver medal with the Qatari relay at the Asian Indoor & Martial Arts Games in Ashgabat .
In 2018 he took part in the Asian Indoor Championships in Tehran , where he won the bronze medal over 400 meters and gold in the relay. At the end of August he took part again in the Asian Games in Jakarta , where he was eliminated in the semifinals over 400 meters with 46.33 seconds and won the Katartian relay with a new Asian record of 3: 00.56 minutes ahead of India and Japan. The following year he reached the semi-finals at the Asian Championships in Doha, in which he was eliminated with 47.10 s. With the relay he also took part in the home world championships there in October, but could not qualify for the final with 3: 06.25 min.