M. R. Jayakar was a barrister, Federal Court Judge (1937-9) and member of the Bombay Legislative Assembly. He had been called to the Bar at Lincoln’s Inn in London in 1905. In the 1930s he sent his son, Jayapal, to study in Oxford, having failed to gain admission to Oxford in the early twentieth century himself.

Jayakar became heavily involved in nationalist politics in India. He was known for his sympathies with the Hindu Mahasabha, clashing with Mohammed Ali Jinnah. He was a member of the Hindu Missionary Society in Bombay and leader of the Swaraj Party for a short time, resigning in 1925. In 1930, Jayakar and Tej Bahadur Sapru were involved in negotiations between Congress and the Government when Motilal Nehru and other Congress members were imprisoned. These negotiations are said to have led to the Gandhi-Irwin Pact of March 1931 whereby Congress members were released from prison in return for the discontinuation of non-cooperation; the salt tax was removed and Congress members would be represented at the next Round Table Conference. Jayakar was a member of the Judicial Privy Council in London and attended the Round Table Conference in London in 1931.

Jayakar was known for his educationist and philanthropist work. He received an honorary DCL from Oxford University in 1938, upon the recommendation of E. J. Thompson. He was Vice-Chancellor of Poona University from 1948 upon its foundation, until his retirement in 1955.