Mahtab was born at Agarpada in Bhadrak district on November 21, 1899. After completing school education at Bhadrak High School, he studied in the Ravenshaw College. Quitting study, he joined in freedom struggle in 1921.
He was jailed in 1923-24 for leading Praja Andolon. In 1930-31, he was jailed twice for participating in Salt Satyagraha and Civil Disobedience Movement.
He served the State as Chief Minister two times- first from 1946 to 1950 and then from 1956 to 1961. He was Union Minister of Industries, Commerce and Supplies from 1950 to 1951. He was appointed Governor of Bombay in 1955. He was elected unopposed to the Lok Sabha in 1962. He resigned from Congress in 1966.
His played vital roles in shifting capital from Cuttack to Bhubaneswar, establishing Odisha Textile Mill and All India Radio Centre at Cuttack and construction of Barabati Stadium and Hirakud Dam. He had founded weekly newspaper ‘The Prajatantra’ in 1923.
