He was a Lutheran parish priest in Kvívík and a rural dean in Nes on the Faroese island of Eysturoy before settling in Denmark in 1878.

During the years 1847–1848, and again in 1853, he returned to the Faroe Islands to study the dialects and to collect the native ballads and folklore, which he published in 1851–1855 under the title of Færöiske Kvæder.

[3] In this, Hammershaimb had accepted the advice of the Icelandic independence leader Jón Sigurðsson, who had seen the manuscript for his Bemerkninger med Hensyn til den Færøiske Udtale ("Notes with Respect to Faroese Pronunciation"); Hammershaimb considered that, despite its artificiality, this was the only approach that would overcome the problems of differing dialects in the islands.

[5] In 1886–1891, Hammershaimb published his principal work, Færøsk Anthologi; it incorporated an account of the islands and their inhabitants, a variety of prose and verse in the Faroese language, and a grammar, and – in the second volume – a lexicon by Jakobsen.

Its development was promoted by nationalist agitation, which hastened the restoration of the Faroese Parliament in 1852 and the end of the Danish royal trade monopoly in 1856.