Casper Mortensen was born in Copenhagen, Denmark on December 14, 1989. He played for several Danish teams,growing up to become an elite player. His first steps as a professional were made in 2007 at Ajax Kobenhavn, where he played for two seasons. He then signed for Fredericia HK, where he played for two years, and was chosen best player of the season. From there he went to Viborg HK, where he only played one season, before making the first major leap of his career.
In 2012, a new adventure with the Bjerringbro-Silkeborg began, debuting in the EHF Champions League, and was the top scorer on the team. In 2015 he played his last season in Denmark with SonderjyskE, before moving to the German Bundesliga with HSV Hamburg, where he only played one year. Problems at the German club caused its disappearance in 2016, and Mortensen signed for the German club TSV Hannover-Burgdorf, where he played a leading role and became the highest scorer in the Bundesliga in 2017/18.
Mortensen is a key member of the Danish national team, with which he debuted in 2012. With more than 100 appearances, his biggest honor came when he won the gold medal at the Rio de Janeiro Summer Olympics in 2016.
On May 10, 2018, Mortensen signed with Barça Lassa for three seasons.
The Danish winger stands out because of his speed, which allows him to counterattack with ease. His good physical strength, together with his great ability as a finisher make him a multi-faceted threat. In addition, he specializes in penalty shots.