He came into contact with the Rashtriya Swayamsevak Sangh (RSS) during his student days. He was also a disciple of Swami Agamananda. Parameswaran became an RSS pracharak (full-time organizer) in 1950, as per the direction of M.S. Golwalkar (Guruji), who was the Sarsanghchalak of RSS. He served as organizing secretary of Bharatiya Jana Sangh in 1957. In 1968, he became an All‑India General Secretary and later Vice‑President of the Jan Sangh. He was jailed during the Indian Emergency (1975-1977). In 1977, Parameswaran moved from politics to the sphere of social thought and development. He worked as director based in New Delhi for Deendayal Research Institute an organisation started by Nanaji Deshmukh for four years. P. Parameswaran, a bachelor, who didn't have a house of his own, was residing in the Vichara Kendram headquarters, Thiruvananthapuram.