The earliest recorded history of Kalimpong is small and hazy. It was only after the Anglo-Bhutan War in 1864 that the history of Kalimpong was recorded. Prior to this, some records are available on the history of Kalimpong but these records are very contradictory and are almost impossible to authenticate. It was only after the Treaty of Sinchula on 11 November 1865 that Kalimpong came to be a place of some importance and prominence.

In spite of the different theories put forward by the various scholars and historians, one thing about the history of Kalimpong is certain: ‘that it was a part of the Sikkimese or ‘Donzong’ kingdom which basically was inhabited by three major communities – the Lepchas (who called themselves the ‘Rong’ or the Ravine folk), the Bhutias and the Limbus (Tshongs). The first Chogyal (Divine Ruler) of Sikkim is believed by scholars, to have brought a consolidated rule over the whole of Sikkim which also included the area now known to be Kalimpong’.

One of the later rulers, Tensung Namgyel (born in 1664 and enthroned in 1670) married three times. The first wife, a Tibetan, bore him a daughter, Pende Amo. The second wife, a Sikkimese, bore him a son Chador Namgyel, and the third wife was the daughter of a Limbu king. Chador Namgyel, (born in 1686) succeeded his father in 1700, as a mere child of 14 years. This offended his half-sister Pende Amo, who not only was older but was also the first child of the royal family. She executed an invasion by the Bhutanese who overran the kingdom with the child king having to flee to Tibet. In 1706, Chador Namgyel, now a young man, returned to Sikkim and the Bhutanese were forced to evacuate the entire kingdom west of the river Teesta, though the Bhutanese still maintained their position at the fort of Damsong and retained the area of the kingdom east of the mighty Teesta River. The area still under the Bhutanese rulers was basically the area of present day Kalimpong.

This area in these earlier times was known as Dalimkot and Kalimpong was the name of a very small village which had as its citizens two or three families with 8-9 cows. This village was considered so insignificant that the Ashley Eden of the Bengal Civil Service, made just a flying reference to the village of Kalimpong, in his report to the Secretary to the Government of India. Incidentally, as per the present records available, this was the first time any official reference was made about Kalimpong.

The next reference made about Kalimpong in history, was by Surgeon Rennie, in his book Bhotan and the story of the Dooar War. He too did not find it important enough to show Kalimpong on the map in his book. After the Anglo-Bhutan War of 1864 and the Treaty of Sinchula which was signed the following year, the entire area east of the Teesta River as well as the Doars was ceded to British India and this ceded area was attached to the Western Doars District. In the following year, this area was transferred to the District of Darjeeling. It was only after this that Kalimpong was set on the development track. Some of the important reasons for the sudden development of Kalimpong were:

Kalimpong became an important centre for trade with Tibet due to the closeness of the town to the Jelepla Pass which allowed access to Central Tibet. The British government decided to open up Kalimpong as an alternative Hill Station to Darjeeling. The coming of the Scottish Missionaries who did significant work for the development of Kalimpong, and The British Government opened up Kalimpong for settlers from other places who came in large numbers and with their hard work and skill made Kalimpong what it is today.

Kalimpong offered easy access to the Chumbi Valley of Tibet via the Jelepla Pass, which is about a 100 km away from Kalimpong town. Hence trade with Tibet was channelized through Kalimpong. Musk, wool, fur, food grains, etc, that were carried on mules, were traded in Kalimpong. This sudden economic prosperity of the town attracted the plainsmen and others to flock into Kalimpong. The decision to develop Kalimpong as a hill station too prompted well-to-do families from the plains and as well as British Officers to frequent and build summer cottages in Kalimpong.

The Scottish Missionaries too played a big part in the development of Kalimpong by starting various primary schools and welfare centers in Kalimpong. The Scottish University Mission Institution was started in 1886 and in a few years’ time, the Kalimpong Girls High School was established. In the year 1900, Rev. J. A. Graham, founded the present Dr. Graham’s Homes, which was aimed to be a school cum orphanage for destitute Anglo-Indian children. All these attracted people into Kalimpong in large numbers and by 1907, it was no longer the same old Kalimpong. By 1911 it had an official population of 7880 people. Kalimpong was made a sub-division in the year 1916.

The economic development of Kalimpong took a back seat following the Chinese aggression in 1962 after which trade through Jelepla was closed. Today, Kalimpong relies mostly on the business generated by the educational institutes, tourism and agriculture but it still retains its peaceful and relaxed way of life. The 2011 census puts the population of Kalimpong sub-division (now a full-fledges district) at 2,51,642 while the population of the town is 49,403.

In 2017, the Honourable Chief Minister of West Bengal, Mamata Bannerjee, out of genuine love and appreciation for Kalimpong, upgraded Kalimpong into a district after which it has been put on the fast track to development.