Biswanath Das was associated with Indian National Congress and participated in the non-cooperation movement and Salt Satyagraha. From 1921 to 1931 he was the member of Mandraj legislative council. In the first provincial Government election in 1937 he was elected in the Orissa Legislative Assembly and was appointed as the Chief Minister of Orissa. After two years he resigned from this post. In 1942 Biswanath Das actively took part in the Quit-India movement and imprisoned by the British rulers. In 1952 he was appointed as the president of the Utkal Congress Committee. In 1961 Biswanath Das again won the election and became the member of the Orissa legislative assembly. In the following year he was appointed as the Governor of Uttar Pradesh and served six years in this post.
In 1966 Biswanath Das was selected as the president of All India Lok Sevak Mandal. During the time of political instability in Orissa he was again appointed as the Chief Minister of Orissa. He enacted several laws to protect the farmers. To spread Sanskrit education Biswanath Das donated one lakh Rupees. Biswanath Das loved the Indian culture and religion and was associated with many cultural organizations. He established Presidency Ryot Association and Andra Zamindari Ryots Association to protest against zamindary System.