Marek Kuszewski won all his international honors in team sabre. He won Olympic silvers with the Polish team in 1956 and 1960, World Championships silver in 1954 and bronze in 1957. Domestically, Kuszewski never won an individual Polish sabre title, placing second at the 1954, 1955 and 1960 Polish Championships and winning bronzes in 1956 and 1959, but he won a team title in 1951.
After retiring from sports, Kuszewski, who graduated from the University of Wrocław with a Polish philology degree in 1956, worked as a journalist. Kuszewski became a member of Polish Olympic Academy in 1984 and was also active with the Polish Olympic Committee.