Mainpuri district (Hindi pronunciation: [mɛːn̪.pʊɾiː]) is one of the districts in the Agra division of Uttar Pradesh, India. Mainpuri town is the district headquarters. Mainpuri is located in the southwestern part of Uttar Pradesh, within the Agra division. It is situated in the Ganges-Yamuna Doab region. It consists of six tehsils, namely Mainpuri, Bhongaon, Karhal, Kishni, Kurawali and Ghiror.

Mainpuri forms part of the ancient legendary region of Lord Krishna's land called Braj. It is bounded on the north by Etah district, on the east by the districts Farrukhabad and Kannauj, on the south by Etawah district and on the west by the districts Firozabad and Etah. It lies between north latitude 260 53′ to 270 31′ and east longitude 780 27′ to 790 26′. According to the 2011 census, Mainpuri district has a population of 1,847,194. The district has a population density of 670 inhabitants per square kilometre (1,700/sq mi). Mainpuri has a sex ratio of 876 females for every 1000 males, and a literacy rate of 78.26%.

Mainpuri district was formed in 1837, when the massive Etawah district was divided. Mainpuri itself had previously been the seat of Etawah district since 1801, when the British had annexed the territory from the Nawab of Awadh. Another major change was when Etah district was split off in 1845.

Several copper harpoons and antenna swords have been found in Ganeshpur village in 2022 which are from Copper Hoard Culture. Mainpuri formed part of the kingdom of Kanauj, and after its fall it was divided into a number of petty principalities, of which Rapri and Bhongaon were chief. In 1194 Rapri was made the seat of a Muslim governor. Mainpuri fell to the (Mughal)Babur’s invasion in 1526, and, although temporarily wrested from them by the short-lived Afghan dynasty of Sher Shah, was again occupied by them on the reinstatement of Humayun after the victory of Panipat. Like the rest of the lower Doab, towards the end of the 18th century Mainpuri passed into the power of the Maratha Empire and finally became a portion of the province of Oudh. When this part of the country was ceded to the British in 1801, Mainpuri town became the headquarters of the extensive district of Etawah, which was in 1856 reduced by the formation of Etah and Mainpuri into separate collectorates. On the outbreak of the mutiny in 1857, the regiment stationed at Mainpuri revolted and attacked the town, which was successfully defended by the few Europeans of the station for a week, until the arrival of the Jhansi mutineers made it necessary to abandon the district.

Kak Nadi, Senghar Nadi, and Sehar Nadi were some of the rivers in the area which have since dried up.

The Mainpuri district is headed by an IAS officer of the rank of District Magistrate (DM). The district is further sub-divided into sub-divisions or Tehsils, each headed by a Sub Divisional Magistrate (SDM).

These Tehsils are further divided into Blocks, each headed by a Block development officer (BDO).

The six sub-divisions or Tehsils in Mainpuri are as follows: