Narayanaswamy won the Bangarapet Assembly constituency representing the Indian National Congress in the 2023 Karnataka Legislative Assembly election. He polled 77,292 votes and defeated his nearest rival, M. Mallesh Babu of the Janata Dal (Secular), by a margin of 4,711 votes.[4][5][6][7] He first became an MLA winning the 2013 Karnataka Legislative Assembly election representing the Indian National Congress from Bangarapet. He polled 71,570 votes and defeated his closest opponent, Em Narayanaswamy of the Bharatiya Janata Party, by a margin of 28,377 votes.[8][9] He retained the seat for the Congress in the 2018 Karnataka Legislative Assembly election. He polled 71,171 votes and defeated M. Mallesh Babu of the Janata Dal (Secular) by a margin of 21,871 votes. He won for the third time in 2023 election.[10] He was named in the list as SN Narayanaswamy KM as another SN Narayanaswamy V, too contested the same election, as an independent.[10][11]
He was appointed chairman for Karnataka Urban Infrastructure Development and Finance Corporation (KUIDFC) on 26 January 2024.[12]