Kotdwar is a city, municipal corporation in Pauri Garhwal district of Uttarakhand, India. It is just 101 km from Pauri, the district headquarter. It is the eighth-largest city in Uttarakhand. Its old name was "Kootdwar", which means the gateway of the high hill Koot since it is located on the bank of river Khoh. It is situated in the southwestern part of the state and is one of the main entrance points in the state of Uttarakhand.

Initially isolated and less known, it came into prominence when it was connected with rails in 1890 by the British.

Kotdwar is famous for its well-known and holy Sidhbali Temple which is situated 2 km (1.2 mi) from Kotdwar. Sidhbali Temple is dedicated to Lord Hanuman and is visited by millions of believers all around the year.

Kotdwar translates to Gateway to Garhwal because the town is located in the foothills of Pauri Garhwal region in Uttarakhand.

The city was initially ruled by the Mauryan Empire under the Great Ashoka, followed by the rule of Katyuri dynasty and then the Panwar dynasty of Garhwal.

Gurkhas reigned Kotdwar for almost 12 years, after which the British defeated them and took control over the region. The Kotdwar Railway Station established by the British is one of the oldest in India. It was mainly used for transporting timber from Garhwal. The first passenger train ran in 1901.

Kotdwar is at foothills of Himalayas. The city's total area is 80 km² (31 sq mi). By road Kotdwar is 216 km (134 mi) North of Delhi, 120 km (75 mi) South of Dehradun, 208 km (129 mi) West of Nainital, 99 km (62 mi) East of Roorkee.

Kotdwar lies on the western margin of the Himalayas, at an altitude of 454 m (1,490 ft) above sea level.