The area flourished from the
Jomon period. A settlement of
Ainu people existed along the southeast Hiroo River. It was part of
Matsumae Domain in the
Edo period and was on a road opened by the
Tokugawa shogunate along the coast to
Kushiro. It was the site of a ''
jin'ya'' established to govern the entire
Tokachi Province. During the
Bakumatsu period in 1858, it was awarded to
Sendai Domain, which relocated farmers, carpenters, and woodsmen to the area and began cultivating grain and vegetables. In 1906, the village of Moyori was established under the second-class town and village system. Its name was changed to Hiroo Village in 1926, and was elevated to town status in 1946. The
2011 Tohoku earthquake and tsunami resulted in a 2.8m tsunami striking Hiroo, causing over 1 billion yen in damage. ==Government==