Historically, Kolar was also called as Kolahala, Kuvalala and Kolala. It was the capital of the Gangas until the 4th century AD. The Cholas ruled over the region from 1004 AD to 1116 AD. After that, Vishnuvardhana (1108-1142 AD) conquered the area. Kolaramma Temple and Someshwara Temple are two important temples of the district. It was believed that Kolar came into existence in 2nd century AD also. In 1117 AD, Kolar came under the control of the Hoysalas and was partitioned into two parts in 1117 AD. Vijaynagar rulers kept control on the region from 1336 to 1664. Maratha ruled the region in the 17th Century. The region was under the Muslim rule for a long period of seventy years. The region was also ruled over by the Nawab of Cuddapah, Nizam of Hyderabad and Hyder Ali.

The district also has given birth to some famous personalities who belong to different fields. Jockin Arputham is a social worker who has worked for more than 40 years in slums and shanty towns. He was honored with many prestigious wards likewise, Ramon Magsaysay Award for Peace and International Understanding in 2000 and Padma Shri award in 2011. Kuppur Yalappa Narayanaswamy is a renowned Kannada poet, scholar, critic, and playwright and currently a Kannada professor in the Government Arts College in Bangalore. He was privileged with the most esteemed award i.e. Sahitya Akademi Award.

Geographically, the district encompasses a total geographical area of 3,979 sq. km. and occupies the ranks 26th in State and 309th in India on the basis of the geographical size. It lies at 13°14' N latitude, 78°13' E longitude and 821 m altitude. In the year 2021, there was a total 9.64% forest area of total geographical area. The district is bounded by the Bangalore Rural district in the West, Chikballapur district in the North, Chittoor District of Andhra Pradesh in the East and Krishnagiri of Tamil Nadu in the South. The important rivers of the district which originates from the elevated regions are Palar, Uttara Pinakini and Dakshina Pinakini. The actual rainfall in the district was 1484.8 mm in the year of 2021-22. Most of its rainfall occurs in the monsoon season.

Administrative wise, the district is divided into 5 sub-districts namely Kolar, Bangarpet, Malur, Mulbagal and Srinivaspura. Moreover, it has 7 towns and 1,608 villages. Kannada is its official language. Kolar came into existence on the 1st November, 1956 in the state of Karnataka. Its administrative headquarters is located at Kolar, situated at a distance of 66 km. from the state capital.

Demographically, according to 2011 census, the district has a total number of 3,30,990 households with a total population of 15,36,401 comprising 7,76,396 are males and 7,60,005 are females. The population growth rate during the period 2001-2011 was 10.77% including 10.65% were males and 10.89% were females. The density of population of the district is 386 persons per sq. km. The sex ratio is pegged at 979 (females per 1000 males) while the child ratio stands at 962 (females per 1000 males). As per 2011 census the percentage of major religions practiced by the people of this region is Hindu at 84.97% and Muslim at 13.01%. According to 2011 census, the percentage of the principal languages spoken in the region is Kannada at 51.51% and Telugu at 22.67%. In the year 2020 the number of live births in the district was 22,463 out of which 11,785 were males and 10,678 were females. In the same year the number of deaths in the district was 12,007 out of which 7,433 were males and 4,574 were females.

Economically, the district is dependent on agriculture, dairy, sericulture and floriculture primarily. It is also called the land of "Silk, Milk and Gold". Only bore well water is available for irrigation and drinking. It had gold mines in Kolar Gold Fields which were closed in the 2003. The district has two major industrial areas i.e. minor Industrial Areas and medium Industrial Area such as Narasapura Industrial Area, Vemagal Industrial Area, Tamaka Industrial Area and Malur Industrial Area. Honda, Indian Railway, Karnataka Milk Federation, BHEL, Power Grid Cooperation, Mahindra Aerospace and Volkswagen India are some of the major industries of the district. In the year 2019-20 the gross domestic product in the district was Rs. 27,13,088 lakhs at current price and Rs. 19,46,397 lakhs at constant prices in the year 2011-2012. The net domestic product in the district during the period 2019-20 was Rs. 23,62,437 lakh at current price and Rs. 16,62,092 lakh at constant prices in the year 2011-2012. The Per Capita Income or NDDP, At Factor Cost during the period 2019-20 was Rs. 1,42,114 at current price and Rs. 99,984 at constant prices in the year 2011-2012.

Education wise, according to 2011 census, the literacy rate in the district is 74.39% out of which 81.81% are males and 66.84% are females. The total literate population of the district is 10,16,219 including 5,64,110 are males and 4,52,109 are females.

K. S. Vasan was an Indian communist politician and trade unionist from the Kolar Gold Fields. He formed the first leftist trade union in 1940s. He became the member of the Communist Party of India (Marxist) after the disintegration of the Communist party. Kyasamballi Chengalaraya Reddy was the first Chief Minister of Karnataka and also served as the president of Mysore Congress twice i.e. in 1937-38 and in 1946-47. Cadambi Sheshachar Venkatachari was an Indian Civil Servant and diplomat. He also served as the Chief Minister of Rajasthan from 6th January, 1951 to 25th April, 1951.

The district has a number of historical and religious places to visit which allure travellers from different parts of the country. These places are Kolaramma Temple, Someshwara Temple, Antharagange, Avani, Kolar Gold Mines, Kotilingeshwara Temple, Bethamangala, Mulbagal, Virupaksha Temple, Kurudumale, BangaruTirupati, ChikkaTirupati and Budikote Village. During the year 2016, there were 2 foreign tourists and 19,60,058 domestic tourists who visited the above places.