[4] The parish of Mo was established as a municipality on 1 January 1838 (see formannskapsdistrikt law).

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

The name is identical with the word mór which means "heath" or "moorland".

[7] The municipal council (Herredsstyre) of Mo was made up of 21 representatives that were elected to four year terms.

The tables below show the historical composition of the council by political party.