 He entered politics while a student, and had been an active member of the Students Organisation since 1946.Sankaranarayanan became elected to 5th KLA from Thrithala, 6th KLA from Sreekrishnapuram, 8th KLA from Ottappalam and later, also to the 11th KLA, from Palghat constituency as Indian National Congress member.From 11 April 1977 to 25 April 1977 he handled the portfolios of Agriculture, Animal Husbandry and Dairy Development and Community Development, in the Ministry headed by K Karunakaran.