[2] The first settlement at Klaksvík dates back to Viking times, but it was not until the 20th century that the district merged to form a large, modern Faroese town that became a cultural and commercial centre for the Northern Isles and the Faroe Islands as a whole.

In time, they grew into four villages: Vágur, Myrkjanoyri, Gerðar and Uppsalir; which finally merged to form the town of Klaksvík in 1938.

Since August 2007, when Restorffs Bryggjarí went out of business, Föroya Bjór has been the only producer of beer and soft drinks in the Faroe Islands.

With the opening of the Leirvík sub-sea tunnel, the Norðoyatunnilin in April 2006, Klaksvík gained a physical link with the mainland of the Faroe Islands and can now be considered one of its key ports.

The roof construction is the same as that found in the Viking halls, and which has survived in Faroese smoke rooms (kitchens) and village churches.

The bus services and the ferry to Kalsoy are operated by Strandfaraskip Landsins, the public transport company of the Faroe Islands.

In August 2023, KÍ became the first Faroese side to play in the group stages of a European competition, after their win against BK Häcken in the second qualifying round of the UEFA Champions League.