[1] At club level, he has won major titles in four countries, including league championships in Norway, Denmark, France and Germany.

Sagosen was signed in an ambition to reach the EHF Champions League.I His time there was however a mixed bag.

[7] Sagosen made his debut for the Norwegian national team in 2013 against Croatia during the Bring Cup.

[9] At the 2016 European Championship, Norway placed fourth and Sagosen was awarded a spot on the All-Star team of the tournament as best centre back.

At the 2019 World Championship, Norway finished second and Sagosen was included on the All-Star team as best left back for a second time.

Norway placed third at the 2020 European Championship, where Sagosen was the top scorer with 65 goals and included on the All-Star team for a fifth consecutive major international tournament.