Sathyan was born in a Christian family at Aramada, Thrikkannapuram, Thiruvananthapuram on 9 November 1912 as the first child of Cheruvilakathu Veettil Manuel and Emily. He has four siblings named Chellayya, Neshan, Devadas, and Jacob. Sathyan passed the "Vidwan" exam, equivalent to Master of Arts before joining Saint Joseph's School, Trivandrum as a teacher. After some time, he got job as a clerk in the Kerala Secretariat and worked there for about a year. He joined the army in 1941 and got posted as a Commissioned Officer of the Viceroy of India. He served the British army in Manipur, Burma (now Myanmar) and British Malaya (now Malaysia) during the World War II period. After finishing his term in the army, he returned home and joined the then Travancore State Police as a police inspector. During the Punnapra-Vayalar uprising in 1947–1948, Sathyan was the inspector at Alappuzha North Police Station.