Kasper Antonsen (born 13 April 1994) is a Danish badminton player. Together with his brother Anders Antonsen, he started his career in badminton in Viby, learned from his father who worked at one of the badminton clubs in Denmark. Antonsen who trained at the Aarhus AB, made his professional debut in 2012, and later, he won the gold medals at the 2013 European Junior Championships in the boys' doubles and mixed team events, also a bronze medal in the mixed doubles event.