He was the son of the merchant Peter Hans Dahl and Elisabeth Súsanna Vilhelm.

Dahl was a classmate of Janus Djurhuus at the high school in Tórshavn, the capital of the Faroes.

Djurhuus described Dahl’s delivery of the nationalist hymn Nú er tann stundin komin til handa by Jóannes Patursson as his "linguistic baptism".

Subsequently, he started the translation of the Old Testament, but was unable to finish it prior to his death in 1944.

In addition Jákup Dahl translated dozens of church songs, including some by Martin Luther into his native language.