Zachariassen started playing handball at Ulkebøl I&UF before joining HF Sønderborg and later
SønderjyskE Håndbold in the
Danish second tier. In 2011 he was promoted to the
Herrehåndboldligaen. In the 2013-14 he was included in the league All-star team as the pivot. In 2014 he joined German
Bundesliga team
SG Flensburg-Handewitt on a three year deal to replace his compatriate
Michael V. Knudsen on a three year deal. He was named Player of the Season by fans in his first season with SG Flensburg-Handewitt. With Flensburg he won the 2014-15
DHB-Pokal and the
German Championship in 2018 and 2019. In 2020 he returned to Denmark to join
GOG Håndbold. In 2019 he won the
Danish Men's Handball Cup and was named MVP for the tournament. In 2022 and 2023 he won the
Danish Championship, and in 2023 the Danish cup once again. In 2024 he joined
Bjerringbro-Silkeborg.
National team Zachariassen debuted for the U21 Danish team on March 11th, 2011 against Portugal. At the 2011 U21 World Championship he won silver medals with the Danish team. At the
2019 and
2021 World Championships he won back-to-back World Championships. The 2019 were the first time Denmark won the title. ==References==