Marcel Mayack gained his first international experience at the Summer Universiade 2015 in Gwangju , where he was eliminated in the long and triple jump with 7.28 m and 14.69 m, as well as in the high jump with 2.00 m. Two years later, at the Islamic Solidarity Games in Baku , he finished tenth in the long jump with 7.20 m and eleventh in the triple jump with 15.28 m. At the Francophonie Games in Abidjan , he jumped in the long jump with 7.57 m to fifth place and finished ninth in the triple jump with 15.37 m. At the Student World Games in Taipei , he finished tenth in the final in the long and triple jump, while he failed again in the qualification in the high jump with 2.05 m. In 2018 he took part in the Commonwealth Games in the Australian Gold Coast for the first time, winning the bronze medal in the triple jump with 16.80 m. He then finished eighth in the long jump at the African Championships in Asaba with 7.69 m and sixth with 16.40 m in the triple jump. The following year he took part in the Africa Games in Rabat for the first time , where he finished seventh in the triple jump with 15.99 m, while he was eliminated in the long jump with 6.94 m in qualification. He was then at the Military World Games in Wuhan with 15.63 m twelfth in the triple jump and retired in the long jump with 7.07 m in the qualification.