Career
Danielsen started with KÍ Klaksvík, playing his first game in their 2000 league season. After he became a regular in the national team he was loaned to Norwegian side Sogndal before he signed for Danish outfit Boldklubben Frem. In the wintertransfer 2010, he signed Football Club Roskilde.
Danielsen is a regular in the Faroese national team
He made his debut in April 2003 in friendly match against Kazakhstan, coming on as a substitute for Hans Fróði Hansen.