K. P. S. Menon joined Oxford after the end of the First World War. He was President of the Oxford Majlis for a term in 1920.
Menon served in the Madras ICS until 1924 when he was transferred to the Foreign and Political Department as Under-Secretary to the Resident of Hyderabad. In 1939, he was appointed as Chief Minister of Bharatpur, then Ambassador to China after independence, Foreign Secretary from 1948 to 1952 and then Ambassador to Moscow.