Itahari (ईटहरी) is a sub-metropolitan city in the Sunsari District of Koshi Province of Nepal. Itahari city is the business hub of eastern Nepal. It is the second most populous city in Eastern Nepal after Biratnagar. Situated at a distance of 25 kilometres north of the provincial capital of Biratnagar, 16 kilometres south of Dharan and 92 kilometres west of Kakarbhitta, Itahari serves as a junction point of the east-west Mahendra Highway and the north–south Koshi Highway. Itahari has an estimated city population of 1,98,098 living in 40,207 households as per 2021 Nepal census. It is one of the fastest growing cities of Eastern Nepal. It is one of the cities of the Greater Birat Development Area which incorporates the cities of Biratnagar-Itahari-Gothgau-Biratchowk-Dharan primarily located on the Koshi Highway in Eastern Nepal, with an estimated total urban agglomerated population of 804,300 people living in 159,332 households.
According to the Ministry of Federal Affairs and Local Development, Itahari has an area of with 140,517 people living in 33,794 individual households as of Census of Nepal 2011. The town is divided into a total of 20 wards. The municipality was established in 1997 and became a sub-metro in 2014 after merging the VDCs of Khanar, Ekamba, Pakali and Hansposa.
Itahari is a fast-growing town in eastern Nepal. .It is situated in a fertile plain. Located at the main transportation junction in eastern Nepal, the town is gaining importance as a traffic hub. Being at the junction of the Mahendra Highway and the Koshi Highway, the town is of emerging importance. Itahari is at distance from Jogbani, India by road which connects Itahari to Kolkata seaport by road and rail both
means of transportation.
Biratnagar Airport is the nearest airport which is situated at 23 km distance from Itahari. Itahari is the junction of eastern development region.
In the winter season, the temperature of Itahari is 10–18 °C, it increases to 30–42 °C during the summer season. About 2007 mm of precipitation falls annually.