B.B. Gurung was born on 11th October 1929 at Chakung, West Sikkim. He graduated form Calcutta University in humanities/arts and initially served as a school teacher at Turnbull School Darjeeling and later one year in Rangpo High School between 1951 and 1955. Leaving teaching profession Gurung joined journalism and worked as a Staff Reporter to the Calcutta based Amrita Bazar Patrika. He was also associated with literature and edited a Nepali Magazine Kanchenjunga. He also edited a book titled ‘Sikkim Past and Present’. He is married and has three sons and a daughter.

Gurung took active part in politics of Sikkim and because of his political inclination he joined in his 20s Sikkim Rajya Congress under the leadership of Kashi Raj Pradhan and became General Secretary of the Party.

He came under the influence and association of  Kazi Lhendup Dorjee led Sikkim Rastriya (National) Party and was elected a Councillor for the first time from his native constituency Chakung. As a result he was appointed Executive Councillor by the then Chogyal to look after Education, Forest and Transport Departments - which he carried out to the tallest satisfaction of Chogyal and the people of Sikkim.

The political upheaval which sparked off after the fifth general election and in 1972 under the leadership of Kazi Lhendup Dorji led Sikkim National Congress caused complete breakdown of law and order in Sikkim. Gurung joined this pro-democratic movement of Sikkim and was one of the signatories to sign the historic May, 8, Agreement 1973-the Tripartite Agreement of the Chogyal, by the leaders of political parties and the Government of India to establish a Constitutional Monarchy and Parliamentary Democracy in Sikkim to frame a constitution, to guarantee fundamental rights, rule of law, independence of judiciary, legislature and executive powers to elected representatives and adult franchise based on ‘One Man One Vote’.

As one of the responsible signatories alongwith L.D. Kazi, K.C. Pradhan and others to the agreement B.B. Gurung stood for the cause of introducing a clear cut parity in the Sikkim Assembly by which a new parity formula got evolved to reserve 15 seats for Bhutia - Lepcha, 15 for Nepalese (of Sikkim origin), 1 for Sangha and 1 for Scheduled Castes (Nepalese).

Election to the Sikkim Assembly under the 1973 May Agreement was held in 1974 and Gurung was elected to it-one among the 31 members of Sikkim National Congress under the leadership of L.D. Kazi. Later from October 1977 to 1979 Gurung was appointed Speaker on the demise of C.S. Roy the then Speaker of the Assembly.

Gurung was quite active in the politics of Sikkim between 1973 and 1975 and was instrumental in making Sikkim an associate State of India in 1974 and

later a part of Indian Federal Politics i.e. 22nd State of the Indian Union in the year 1975.

In the historic October 1979 Sikkim Legislative Assembly election B.B. Gurung was elected from two constituencies viz Chakung and Jorethang and for the first time established a singular distinction of winning from two constituencies. He retained Jorethang Constituency and served as a M.L.A. of Sikkim Congress Revolutionary of R.C. Poudyal. When N.B. Bhandari’s Sikkim Janta Parishad defected to Congress-I, Gurung also defected to Congress-I and was offered a Cabinet Ministerial berth in the year 1983 to hold the portfolio Finance.

In a surprise move the then Governor of Sikkim Homi. J.H. Taleyarkhan dismissed N.B. Bhandari as Chief Minister under article 164 (1) of the Constitution on the ground that Bhandari ceased to command the pleasure of the Governor and the same Governor under the same provision of the Constitution of India appointed Mr. B.B. Gurung as the Chief Minister of Sikkim on 11th May 1984 – the third Chief Minister of Sikkim. Gurung’s 14 days Ministry consisted of 9 Cabinet Ministers. Soon after assuming the office of the Chief Minister, Gurung reiterated that his Government support the demands of the people of Sikkim and continue to fight for the "Just demands" of the people. He also stated that his approach with the Center in dealing with various problems of the State would be of cooperation and consultation but not confrontation.

B.B. Gurung in his short tenure as the Chief Minister of Sikkim accorded to an order to the Central Bureau of Investigation to peruse and investigate the alleged charges of corruption against N.B. Bhandari. Under Delhi Police Establishment Act, 1946, it was directed by Gurung’s Cabinet to take up cases by CBI for investigation relating to various offences committed by Bhandari. Further, it was pointed out by Gurung that N.B. Bhandari had acquired wealth/asset disproportionate to his known sources of income in his name and wife. B.B. Gurung along with Mr. L. D. Kazi sought the direct intervention by the then Prime Minister P.V. Narasimha Rao on Bhandari and the then RDD secretary Mr. P.K. Pradhan.

Gurung’s political career despite occasional defections, reflect his identification for protection of both minority and majority communities of Sikkim in regard to various issues. Unfortunately, owing to lack of support and instability, finally the then Governor of Sikkim recommended for imposition of President’s Rule in the State of Sikkim under Article 356 of the Constitution of India on 25th May 1984.