On 1 January 1964, the part of Hattfjelldal on the north side of the lake Røsvatnet (population: 168) was transferred to the neighboring Hemnes Municipality.

[8] The municipality (originally the parish) is named after the old Hattfjelldalen farm (referred to as "Hatfieldalen" in 1723) where the first Hattfjelldal Church was built.

[10] On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Hatfjelldal (removing the definite form ending).

[12] On 14 June 2019, the national government approved a resolution to add a co-equal, official Southern Sami language name for the municipality: Aarborte.

It is called Aarborte when it is spelled alone, but it is Aarborten tjїelte when using the Sami language equivalent to "Hattfjelldal Municipality".

The official blazon is "Per fess argent and vert embattled with one battlement" (Norwegian: Delt av sølv og grønt ved tindesnitt med en enkelt tinde).

The field above the line has a tincture of argent which means it is commonly colored white, but if it is made out of metal, then silver is used.

The arms were designed to mimic the local Hattfjellet mountain which rises above the terrain and can be seen for great distances.

Other lakes in the region include Daningen, Elsvatnet, Famnvatnet, Jengelvatnet, Kjerringvatnet, Krutvatnet, Ranseren, Simskardvatnet, and Unkervatnet.

There are several nature reserves, such as Varnvassdalen with a varied topography and old growth forest of pine, birch and some spruce.