Hosur is a town and a municipality in Krishnagiri district in the Indian state of Tamil Nadu. It is the headquarters of the Hosur Taluk of Krishnagiri district. It is located about 40 kilometres (25 mi) south east of Bangalore, 48 kilometres (30 mi) north west of Krishnagiri and 306 kilometres (190 mi) west of Chennai, the state capital. Hosur is known for its expanding manufacturing industries and its pleasant climate.

The name of the town is from Kannada language which means 'New settlement/town' (ಹೊಸ-New ಊರು-Town).

Rock paintings and carvings suggest that the area has been occupied during the Paleolithic, Neolithic, and Mesolithic ages.

Hosur experiences a tropical savanna climate (Köppen climate classification Aw) with distinct wet and dry seasons. Due to its high elevation, Hosur usually enjoys a more moderate climate throughout the year, with occasional heat waves. The coolest month is January with an average low temperature of 17.1 °C and the hottest month is April with an average high temperature of 33.6 °C. Winter temperatures rarely drop below 12 °C, and summer temperatures seldom exceed 36 °C. Hosur receives rainfall from both the northeast and the southwest monsoons and the wettest months are September, October and August, in that order. The summer heat is moderated by fairly frequent thunderstorms but no flooding. Humidity is 31% and average rainfall is 84 cm.