In 1974, Radhakrishnan was elected to the Jan Sangh's state executive committee. He joined the
Bharatiya Janata Party (BJP) after it was founded in 1980, and became an aide to
Atal Bihari Vajpayee.
Member of parliament (1998-2004) In the
1998 elections, Radhakrishnan was elected to the
Lok Sabha, representing
Coimbatore. The election was held in the aftermath of the
1998 Coimbatore bombings. He defeated the
Dravida Munnetra Kazhagam (DMK) candidate by a margin of 144,676 votes. He was one of three BJP candidates to win in Tamil Nadu as a part of the party's alliance with the
All India Anna Dravida Munnetra Kazhagam (AIADMK). Representing the BJP, he won the
1999 elections from the same constitutency as a part of the DMK-led alliance. He was part of a parliamentary delegation to the
United Nations, and addressed the 58th session of the
United Nations General Assembly on 20 October 2003. He was a member of the parliamentary committee for public sector undertakings from 1998 to 2004 and a member of the parliamentary consultative committee for finance. His tenure in the
Parliament of India ended following his defeat in the 2004 general election to
K. Subbarayan of the
Communist Party of India. He was appointed as the state president of the
Tamil Nadu unit of the BJP in 2004 and served in the position till 2006. As the president, he took a
rath yatra for 93 days, advocating the linkage of Indian rivers, eradicating untouchability, and campaigning against terrorism in India. He covered all the parliamentary constituencies of Tamil Nadu during his journey, which faced criticism from the ruling DMK. He was also involved in the organising of the
Kerala state unit of the BJP during the late 2000s. In 2012, he faced court arrest in
Mettupalayam for protesting inaction against culprits who had assaulted an RSS activist. Radhakrishnan was announced as the BJP candidate for Coimbatore in the
2014 general elections. He secured second place after polling 389,701 votes, the highest among the BJP candidates in Tamil Nadu. He contested as the party's candidate from the same constituency in the
2019 general election and lost to
P. R. Natarajan of the CPIM. He was the chairman of the
Coir Board of India, which comes under the
Ministry of Micro, Small and Medium Enterprises, from 2016 to 2020. He also served as a member of the BJP's national executive.
Governorship (2023–2025) On 12 February 2023,
president Droupadi Murmu appointed Radhakrishnan as the
governor of Jharkhand, succeeding
Ramesh Bais, and he took office on 18 February 2023. Following the resignation of
Tamilisai Soundararajan, he held additional responsibilities as the
governor of Telangana and as
lieutenant Governor of Puducherry from 19 March 2024. On 27 July 2024, he was appointed as
governor of Maharashtra.
Jishnu Dev Varma,
Santosh Gangwar, and
Kuniyil Kailashnathan , took over his positions in Telangana, Jharkhand, and Puducherry, respectively. Radhakrishnan resigned as
governor of Maharashtra following his election as the
Vice President of India. == Vice President of India (2025–present) ==