is a small coastal city located in à Âita Prefecture, Kyushu, Japan. , the city had an estimated population of 25,721 in 13082 households, and a population density of 81 persons per km<sup>2</sup>. The total area of the city is .
Kunisaki covers the northeastern part of à Âita Prefecture and almost the eastern half of the Kunisaki Peninsula (excluding the southeastern part), and faces the Gulf of Iyo on the Seto Inland Sea to the north and east. Settlements are scattered in areas near the sea, and the city center is located near the sea in the central eastern part of the city. The western part of the city is located in the central part of the Kunisaki Peninsula and is mountainous. The city center is located approximately 60 km by road (approximately 40 km in a straight line) from à Âita City, the prefectural capital.
Kunisaki has a humid subtropical climate (Köppen climate classification Cfa) with hot summers and cool winters. Precipitation is significant throughout the year, but is somewhat lower in winter. The average annual temperature in Kunisaki is . The average annual rainfall is with June as the wettest month. The temperatures are highest on average in August, at around , and lowest in January, at around . The highest temperature ever recorded in Kunisaki was on 10 August 2013; the coldest temperature ever recorded was on 8 January 2021.
Per Japanese census data, the population of Kunisaki in 2020 is 26,232 people. Kunisaki has been conducting censuses since 1920.
The area of Kunisaki was part of ancient Bungo Province. During the Edo period it was mostly under control of Kitsuki Domain and was ruled by a cadet branch of the Matsudaira clan, with smaller areas administered as tenryà  territory under the direct control of the Tokugawa shogunate. After the Meiji restoration, the village of Kunisaki within Higashikunisaki District, à Âita was established on May 1, 1889 with the creation of the modern municipalities system. It was raised to town status on November 8, 1894. The city of Kunisaki was founded on March 31, 2006, from the merger of the former town of Kunisaki, absorbing the towns of Aki, Kunimi and Musashi (all from Higashikunisaki District).
On June 25, 2008, the City of Kunisaki declared itself a 'Nuclear-free Peace City" in wishing the abolition of nuclear weapons and world permanent peace.
Kunisaki has a mayor-council form of government with a directly elected mayor and a unicameral city council of 18 members. Kunisaki, together with the village of Himeshima, à Âita contributes one member to the à Âita Prefectural Assembly. In terms of national politics, the city is part of the à Âita 3rd district of the lower house of the Diet of Japan.
The main industry is agriculture, including fruit and vegetable cultivation and commercial fishing. Industries include factories operated by Oita Canon and Sony Semiconductor Manufacturing Co., Ltd.
Kunisaki has seven public elementary schools and three public junior high schools and one public high school operated by the city government and one public high school operated by the à Âita Prefectural Board of Education.
Kunisaki has no passenger railway service. The nearest railway stations are Kitsuki Station, à Âgami Station, or Usa Station on the JR Kyushu Nippà  Main Line, each of which has a bus service to the city.