He practiced as a junior advocate under
K. Parasaran, former Attorney General of India. He was a part-time professor at Madras Law College for 7 years. He was directly recruited as district and sessions judge in 1987 and worked as district and sessions judge at Cuddalore, Salem and Coimbatore. Thereafter, he worked as the special officer, Vigilance Cell, Madras High Court. He was elevated as an acting judge of the Madras High Court on 27 September 2000 and appointed a permanent judge on 20 September 2002. He was then further elevated as the Chief Justice of the Orissa High Court and sworn in on 27 February 2013. He was sworn in as a judge of the Supreme Court of India on 19 September 2013. Nagappan, who held a relatively short tenure, retired as a judge of the Supreme Court on 3 October 2016. ==Notable decision==