The city of Ishim was founded in 1687 as Korkina Sloboda. Since 1721, the Nikolskaya Fair began to be held regularly in the settlement. In 1782, Korkina Sloboda, by decree of Catherine II, was renamed the city of Ishim, the county town of the Ishim district of the Tobolsk governorate, later the Tobolsk province. The name of the city was given by the name of the river on which it is located.
The favorable geographical position of the city, located on the main Siberian highway, among the richest agricultural and cattle-breeding districts of the Tobolsk province, led to its transformation into a major center of fair trade throughout Western Siberia. In the XIX century, in December, the Nikolskaya Fair was held annually in Ishim.
On October 21, 1875, the Ishim City Bank opened. By the end of the XIX century, there were five tanneries, four soap-making, six sheepskin, eight pimokat, sixteen blacksmith, eight brick, two vodka, two candle, two butter crufts and one brewery in Ishim. In the period from 1817 to 1871, educational institutions appeared in the city: a county school, a parish school, a women's gymnasium, a theological school.
According to the first All-Russian Population Census, in 1897, 7,153 people lived in Ishim, Tobolsk province. In 1910, there were 27 streets, 31 stone houses and 1,145 wooden houses in Ishim.
In 1912, the first trains went by the Tyumen-Omsk railway (later the Omsk Railway) through the Ishim station, located two versts from the city. By 1914, the city's population had grown to 15,920 people.
In 1921, Ishim County became the center of the West Siberian Peasant Uprising. From 1918 to 1923, Ishim was part of the Tyumen province, from 1923 to 1934 — in the Ural region, from 1934 to 1935 — in the Chelyabinsk region, from 1935 to 1944 — in the Omsk region, and from August 14, from 1944 to the present — in the Tyumen region.
On September 17, 1928, the settlements of Alekseevsky and Novoserebryannikovsky (Novoserebryansky) were included in the city limits. Since February 21, 1940, Ishim has been a city of regional significance. On October 19, 1956, the village of Serebryanka and the urban part of the village of Zhilyakovka were transferred to the administrative subordination of the City Council. On October 11, 1973, the village of Dymkovka and the village of Smirnovka were included in the city limits.
During the Great Patriotic War, several evacuated enterprises were located in Ishim. By the Decree of the Presidium of the Supreme Soviet of the USSR dated August 10, 1982, the city of Ishim was awarded the Order of the Badge of Honor. In 1990, Ishim was included in the list of historical inhabited places of Russia.