After completing his education, Gagan Chandra worked as a chief engineer in the office of the
Matin Burn Company founded by
Sir Rajendra. After passing his engineering degree, he served two years of apprenticeship as per government rules, he was the District Engineer of
Jalpaiguri district and the Executive Engineer for
Rajshahi Division. During this time, as a Government official he was responsible for the creation of the railway line between Paunia and
Rangpur. He also designed the old
Jalpaiguri railway station. In 1899, using
Screw piling, he accomplished the nearly impossible objective of building a railway bridge over
Teesta River. Moreover, he was enlisted for the construction of the Tihari way to
Tibet for the
British expedition to Tibet. . His company won a tender of 9
lakh rupees at that time for the construction of a railway bridge over the
Jalangi River in
Krishnanagar. During the construction of the bridge, he protested against the insulting behavior of the high-ranking British officials who came on behalf of the government, and as a result, he became a victim of a conspiracy. As a result of the conspiracy, the British official damaged the bridge. He admitted immense loss and demolished the bridge and rebuilt it at his own expense. To compensate for this loss, he had to sell his house in
Kolkata, the tea garden in
Jalpaiguri and some properties in
Nadia. Journalist
Shishir Kumar Ghosh mentioned this incident in
Amritbazar Patrika and highly praised Gagan Chandra's bright and strong character. He built a bridge over the
Jalda Teesta Jaldhaka River using screw piling, and he also designed the building of
Surendranath College, at the behest of
Surendranath Banerjee himself. He was the architect of the
Radha Gobind Jiu Temple in
Agarpara. Biswas also donated lots of land for expansion of railway line in
Nadia. He donated land and money for the development of the
Badkulla area of
Nadia, which came under his
Zamindari estate. He also established the first
Library,
Post office and a
Primary school in Badkulla. He had founded his palace on the left side of the
Anjana river. He also donated the land on which the
Badkulla railway station stands. The
"Gagan Babu Bazaar", a
bazaar, at
Badkulla was founded by him. He was associated with the
University of Calcutta, serving as both its paper setter as well as its paper examiner for disciplines like
Physics and
Mathematics. He was a colleague of
Surendranath Banerjee,
Bhupendra Nath Bose,
Jatramohan Sen,
Ambica Charan Mazumdar, etc. in the early era of political movements in Bengal and was a foremost early politician of the
Indian National Congress. He was a member of the
Bengal Legislative Council for 30 years. == Personal life ==