Mosjøen's coat of arms was granted by King Olav V on 25 March 1960. Composed by sculptor Arthur Gustavsson, it is blazoned Sable, a cock Argent. The cock is traditionally equipped with red beak, wattles, comb, and claws: the so-called colour of armament. The cock represents watchfulness and fighting spirit. After the merger with Vefsn Municipality in 1962, the same coat of arms was adopted for the newly enlarged Vefsn Municipality.
Mosjøen's coat of arms was granted by King Olav V on 25 March 1960. Composed by sculptor Arthur Gustavsson, it is blazoned Sable, a cock Argent. The cock is traditionally equipped with red beak, wattles, comb, and claws: the so-called colour of armament. The cock represents watchfulness and fighting spirit. After the merger with Vefsn Municipality in 1962, the same coat of arms was adopted for the newly enlarged Vefsn Municipality.