Was born in 1892, the youngest of the five sons of Bhai Gopi Chand, a Sahijdhari Sikh couple of the village of Harial in Gujjarkhan tahsil, Rawalpindi district (now in Pakistan). His father died in 1901 and his brothers, Ganga Singh and the one who became famous as Master Tara Singh, took charge of him and supported him through school. After his primary classes in the village school, Niranjan Singh came to Amritsar where he matriculated at the Khalsa Collegiate School and passed his M.Sc. (chemistry) from the Khalsa College in 1916. He won a scholarship and was sent by the university to Agricultural College, Lyallpur, for research.

In December 1917 he joined Forman Christian College, Lahore, as a lecturer in chemistry, but shifted to Khalsa College, Amritsar, in April 1918. At the call of Mahatma Gandhi for non-cooperation with government, Niranjan Singh cast off his western clothes and started wearing khadi (fabric of home-spun cotton) which remained his dress throughout the rest of his life. He also took part in the Gurdwara Reform movement for which he suffered jail in 1924 in the Jaito campaign.

During the first assembly elections under the Government of India Act, 1935, held in January 1937, Niranjan Singh and a few other professors of the college worked in support of the candidates of the Akali-Congress coalition against the candidates of the Chief Khalsa Diwan, to which the college officially belonged, including its principal spokesman, Sir Sundar Singh Majithia. Sir Sundar Singh carried his seat, and became
a member of the Punjab Government which was formed at the end of the elections. Five of the college faculty were dismissed from service on 10 August 1937. Niranjan Singh was among them. They, with the help of some of the leading Akalis set up a new college at Lahore-the Sikh National College. Niranjan Singh became its Principal and remained at the helm of affairs until the partition of India in 1947.

Niranjan Singh then joined the newly established Punjab University with its headquarters at Solan, and was deputed to run honours classes in chemistry on behalf of the University in Delhi. In 1949 he came to Hoshiarpur as head of the chemistry department at the University College there. In September 1950, he was appointed principal of the Camp College in Delhi from which post he resigned in June 1955. Thereafter he decided to serve in honorary capacity. He worked for a term as principal of Guru Tegh Bahadur Khalsa College in Delhi. In June 1958 he established a new college at Fatehgarh Sahib in memory of the mother of Guru Gobind Singh, Mata Gujari. He raised funds, supervised construction of the buildings, and set up laboratories.

In January 1961, he took over as principal at Khalsa College, Bombay. The college needed a great deal of attention which Niranjan Singh was able to provide. In spite of his training as a scientist, Niranjan Singh retained his interest in literature. He published three novels (Prem Kani, Navan Jug and Navan Samaj) and a collection of short stories entitled Nauri Kanian. After his final farewell to teaching, he settled down to writing full-time. His published works, all in Punjabi, are Shakar Rog di Kahani (Apni Zabani), Divan Yaird Master Tara Singh (1968), Jvan Vikas (1970), Jvan Jugat (1971) and Dharam ate Sdiis da Jor (1976).
Niranjan Singh died in Delhi on 8 March 1979.