The volcanic Osorezan Mountain Range extends across the western and central portion of the city, and includes a number of caldera lakes.

Parts of the city is within the limits of the Shimokita Hantō Quasi-National Park, including Mount Osore, Yagen Valley, and Taijima.

The village of Ōminato was established with the creation of the modern municipalities system on 1 April 1889, and was raised to town status on November 10, 1928.

At the time, it was the only city with a hiragana name (むつ), which was adopted to avoid confusion with the original kanji word Mutsu (陸奥) which indicates the old province that covered most of the modern Tōhoku region.

Mutsu has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 26 members.

In terms of national politics, the city is part of Aomori 1st district of the lower house of the Diet of Japan.

The city is also the location for various facilities of the Japan Atomic Energy Agency, and was the home port for the nuclear powered research vessel Mutsu, until its decommissioning in 1997.