Chamarajanagar is the southernmost district in the state of Karnataka, India. It was carved out of the original larger Mysore District in the year 1998. Chamarajanagar town is the headquarters of this district.It is the third least populous district in Karnataka (out of 30), after Kodagu and Bangalore Rural.

Chamarajanagar was earlier known as Arikottara. Chamaraja Wodeyar, the Wodeyar king of Mysooru was born here and hence this place was renamed after him. The Vijaya Parsvanath Basadi, a holy Jain shrine was constructed by Punisadandanayaka, the commander of the Hoysala king Gangaraja in the year 1117 A.D.

Being the southernmost district of Karnataka, Chamarajanagar district borders the state of Tamil Nadu and Kerala. Specifically, it borders Mysooru district of Karnataka to the west and north, Mandya and Ramanagara districts of Karnataka to the north-east, Dharmapuri district of Tamil Nadu to the east, Salem and Erode districts of Tamil Nadu to the south-east, Nilgiris district of Tamil Nadu to the south and Wayanad district of Kerala to the south-west.

National Highway 209 starts from Bengaluru in Karnataka and ends at NH 7 north of Dindigul in Tamil Nadu pass through the district at Kollegal and ends up at Punajur, the western ghats near the Tamil Nadu – Karnataka border.

Most of the district lies in the leeward region of the Nilgiris and consists of mainly semi-arid rain-dependent flatlands along with forested hills.

According to the 2011 census Chamarajanagar district has a population of 1,020,962, roughly equal to the nation of Cyprus or the US state of Montana.This gives it a ranking of 441st in India (out of a total of 640).The district has a population density of 200 inhabitants per square kilometre (520/sq mi).Its population growth rate over the decade 2001-2011 was 5.75%.Chamarajanagar has a sex ratio of 989 females for every 1000 males, and a literacy rate of 61.12%.

Having a large percentage of forest cover, the district also has a high population of forest-dwelling tribals; prominent among them are the Soligas, Yeravas, Jenu Kurubas and Betta Kurubas. These tribals have their own dialect and their total population is said to be around 82,000.