Yonezawa Domain
The area of present-day Oguni was part of ancient Dewa Province and was ruled as part of Yonezawa Domain during the Edo period. After the start of the Meiji period, most of the area became part of Nishiokitama District, Yamagata Prefecture. The village of Ogunimoto was established on April 1, 1889 with the creation of the modern municipalities system. It was elevated to town status on November 3, 1943, becoming the town of Oguni. It absorbed the neighboring villages of Minamioguni and Kitaoguni on March 31, 1954 and the village of Tsugawa on August 1, 1960.