Okoppe Town was controlled as a fishing ground by the Matsumae Clan during the Hōei era (1704-1711). The first Japanese settlers (Wajin) established themselves in Saru in Meiji 22 (1889), and full-scale development began in Meiji 31 (1898) with the arrival of settlers from prefectures such as Ishikawa, Kochi, and Toyama.
In Meiji 42 (1909), the administrative office for Okoppe Village and two other villages was established by merging the Aza-Okoppe area from Omu, and the Saru and Rurochi areas from Mombetsu. In Taishō 4 (1915), it became Okoppe Village under Hokkaido's second-class municipality system. Later, in Taishō 10 (1921), the JNR Nayoro Line was fully opened, leading to the rapid development of agriculture, forestry, and fisheries.
Although Nishi-Okoppe Village separated from Okoppe Village in Taishō 14 (1925), commerce and industry gradually developed alongside the growth of agriculture, forestry, and fisheries. The town was officially established in Shōwa 26 (1951) and continues to this day.
The town's name, "Okoppe," is a transliteration of the Ainu word "O-u-kot-pe," which means "where the river mouths meet." It is believed to have been named this because, at the time, the Okoppe and Mookoppe rivers converged before flowing into the Sea of Okhotsk.