Solan district is one of the twelve districts of Himachal Pradesh state in northern India. Solan town is the administrative headquarters of the district. The district occupies an area of 1936 km².

The district in its present form comprises of the erstwhile princely states of Bhagal, Bhagat, Kunihar, Kuthar, Mangal, Beja, Mahlog, Nalagarh and parts of Keonthal and Kothi and hilly areas of composite Punjab State which were merged in Himachal Pradesh on the Ist November, 1966 on the reorganisation of composite Punjab on the linguistic basis. Most of these princely state as per history were subjected to the onslaught of Gorkha invasion from the year 1803 to 1805. it was in the year 1815 that after th gorkhas lost to the Britishers, these states were freed and restored tot he respective rulers.

This district came into existence on 1 September, 1972. The district was carved out by amalgamating Solan and Arki tehsils of the erstwhile Mahasu district and Kandaghat and Nalagarh tehsils of the erstwhile Shimla district. The district is divided into 4 sub-divisions: Solan, Nalagarh, Arki and Kandaghat. Solan sub-division comprises Solan and Kasauli tehsils. Nalagarh, Arki and Kandaghat sub-divisions comprise Nalagarh, Arki and Kandaghat tehsils respectively. The district comprises 5 Vidhan Sabha constituencies: Arki, Nalagarh, Doon, Solan and Kasauli. All of these are part of Shimla Lok Sabha constituency.

Solan District derives its name from Solan town which came into existence after the construction of the Cantonment at that palce around the last quarter of the 19th century