It was founded by Prince Yury Dolgorukiy as Gorodets-Meshchyorsky in 1152; it got its name due to its location on the land of the Finno-Ugric tribe of Meshchora.

In the late 14th century the town was destroyed by fires and the Tatar incursions. It was built up again a bit far away and was named New Low Gorodets.

In 1452 the Grand Prince of Moscow Vasily II Vasiliyevich Tyomniy (Blind) presented it to the Tatar Khan Kasim who broke out from the Golden Horde and enrolled in the Russian service in 1446. In 1471 the town was renamed into Kasimov after Khan Kasim.

From the middle of the 15th century till 1681 it was the center of the Kasimov Kingdom, a specific principality on the Oka River.

It was attributed to the Kazan Province In 1708, and then to the Voronezh Province. From 1796 it was the district center of the Ryazan Province.

In 1856 the district town Kasimov of the Ryazan Province had 10 churches, 923 houses, and 89 shops.