[5][6] Fosnes was established as a municipality in the old Nord-Trøndelag county on 1 January 1838 (see formannskapsdistrikt law).

[7] During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee.

The first element is fólgsn which means "hiding place", referring to an inlet behind the farm, where ships could not be seen from the main fjord.

[9][10] The coat of arms was granted on 13 November 1992 and it was in use until 1 January 2020 when the municipality was merged into Namsos.

The official blazon is "Or, a rowlock sable" (Norwegian: I gull en svart åregaffel).

The design was chosen to symbolize the importance of the sea for this coastal municipality where rowing boats were the main form of transportation in the former centuries.

Finally the Society proposed the current coat of arms, which was acceptable to the municipal council.

Fosnes was a coastal municipality located along the Foldafjord, north of the town of Namsos.

The municipal council (Herredsstyre) of Fosnes was made up of 13 representatives that were elected to four year terms.