Nannilam is a key constituency in Thiruvarur district, often serving as a battleground for influential local leaders of the AIADMK and DMK. In the 2021 Assembly elections, AIADMK’s R. Kamaraj (former Minister) won the seat with 1,03,637 votes, defeating DMK’s S. Jothiraman, who secured 99,213 votes. The margin of victory was 4,424 votes. In the 2016 Assembly elections, AIADMK’s R. Kamaraj won with 92,107 votes, defeating DMK’s S. M. B. Duraiarasan, who received 71,031 votes. The margin of victory was 21,076 votes. In the 2011 Assembly elections, AIADMK’s R. Kamaraj secured 92,071 votes, defeating DMK’s R. Elangovan, who received 81,667 votes. The margin of victory stood at 10,404 votes.