[1] Dageby was best known for his role in the leftist "rock orchestra" and theater ensemble Nationalteatern, which toured for the final time in 2022.

He joined Nationalteatern in 1971 as guitar player and soon became the leading member when it came to writing the group's songs, such as "Barn av vår tid" (Children of Our Time) and "Bara om min älskade väntar", a Swedish translation of Bob Dylan's "Tomorrow is a long time".

He was also one of the main songwriters in Tältprojektet (The Tent Project), a musical theater performance on the history of the Swedish working class, which toured the country in mid 1977.

Dageby made his debut as a solo artist in 1983 with the album En dag på sjön.

In addition to his solo work and the many reunions with Nationalteatern, Dageby wrote music for Swedish film and television.