After early education at Barisal High School, he joined the Presidency College, Calcutta and graduated in 1893 with triple Honours in Chemistry, Mathematics and Physics. He passed M.A. Mathematics from Calcutta University; B.L. from University Law College Calcutta in 1897. He started his career as Professor of Rajchandra College where he served during 1903-04. Latter he entered Government service as Deputy Magistrate in 1906. In 1911, he resigned his job and rejoined the Bar and was elected member of Bengal Legislative Council in 1913. In 1914, he presided over Bengal Presidency Muslim League, and from 1913-16 served as Bengal Provincial Muslim League Secretary. From 1916 to 21, he was President of the All-India Muslim League and also presided over All-India Muslim League Delhi session in 1918. He was one of the signatories of the Lucknow Pact of 1916. In 1919, he presided over the Provincial Congress session at Midnapore and became the General Secretary of Indian National Congress. In 1920, was elected member of Reformed Bengal Council, and in the same year presided over the second All-India Khalifat Conference held at Delhi. He became first Education Minister of Bengal under Montague-Chelmsford Reform. In 1924, He founded Krishak Praja Party of which he always remained a President. He participated in the Round Table Conference in 1932-33 held in London. In 1935, he was elected to the Indian Legislative Assembly and in the same year, was elected First Muslim Mayor of Calcutta Corporation in 1937. He was elected Member of Reformed Provincial Assembly and was appointed Chief Minister of Bengal, thus was first Muslim to hold this post since the Battle of Plessey. He held this office from Ist April 1937 to 28th March, 1943. In 1940, moved the historic Pakistan Resolution at Lahore on the occasion of All-India Muslim League annual session. In the same year he presided over Provincial Muslim League session held at Madras. In 1943, resigned from Chief Ministership of Bengal. He was leader of opposition in the Bengal Assembly during Khwaja Nazim-ud-Din Ministry. He rejoined the Muslim League in 1946. After the creation of Pakistan came over to Dacca and joined Dacca High Court and was appointed Advocate-General, Government of East Pakistan. He resigned from the party a few months before 1954 elections. He also resigned from the Muslim League in 1953 and formed Krishak Sramik Party which was one of the constituent parties of the United Front Party. He formed the United Front Ministry on April 2, 1954 which was removed on May 29, 1954. In 1955, he became Interior Minister of Pakistan and took active and leading part in framing the first Constitution of Pakistan. In 1956 he was appointed Governor of East Pakistan for one term. He was Editor of 'Balak' from 1901-06 and joint editor of 'Bharat Subrid' from 1900-03.