O Panneerselvam, popularly known as OPS, was sworn-in Chief Minister after the demise of former Chief Minister and All India Anna Dravida Munnetra Kazhagam (AIADMK) General Secretary J. Jayalalitha. O Panneerselvam started his political career as an activist when he joined Dravid Munnetra Kazhagam (DMK) in 1969. He owned a tea stall and some agricultural land but his active participation in politics brought him closer to mega star and politician M G Ramachandran. After the split from DMK in 1973, he joined AIADMK. He hails from the first generation of leaders who formed AIADMK. He served as chairman in Periyakulam Municipality in 1996. After completing the term of chairmanship in Periyakulam Municipality, he contested legislative assembly elections from Periyakulam Constituency and won.
He was born on 14 January 1951 in Periyakulam. As per Tamil Nadu Assembly website, he has completed his Bachelor of Arts (B.A.) but some political observers claimed that he has passed class 12. He is married to P. Vijayalakshmi and the couple is blessed with three children.
As a trusted aide of J Jayalalitha, he served the Tamil Nadu as Revenue Minister in Jayalalitha government and held the office from 19 May 2001 to 1 September 2001. It was during this time when he was chosen to lead the state during her absence. Supreme Court had barred her from holding the office of Chief Minister as she was convicted in the TANSI land scam. Political opponents accused him of running a puppet government on the directions of Jayalalitha. His tenure as Chief Minister lasted for six months, from 21 September 2001 to 1 March 2002.
Later the Supreme Court overturned the decision and cleared the way for Jayalalitha to lead Tamil Nadu again. She was elected again to Tamil Nadu Legislative Assembly when she won Andipatti constituency in a by-election. From 2 March 2002 to 13 December 2002, he was the Minister of Public Works, Prohibition, and Excise. Subsequently, he was also entrusted with the Revenue department’s charge from 13 December 2002 to 2006.
After AIADMK was defeated in assembly elections in 2006, O Panneerselvam contested from Periyakulam constituency and won. He was also elected leader of the opposition in Tamil Nadu Legislative Assembly for two weeks. After the suspension of AIADMK legislators by the speaker, Jayalalitha, who had decided not to attend Tamil Nadu Assembly, returned to replace him as leader of Opposition.
However, in the assembly elections of 2011, He changed his constituency and got elected from Bodinayakkanur constituency. He served as Finance Minister in the government and held the office from 16 May 2011 to 27 September 2014. He was again entrusted with the responsibility of being Chief Minister of Tamil Nadu on 29 September 2014 when Jayalalitha was convicted in the disproportionate assets case. On 22 May 2015, he resigned as Chief Minister and Jayalalithaa was sworn in again after the Karnataka High Court acquitted her in the disproportionate assets case on 11 May 2015.
A year after his resignation, on 23 May 2016, he was sworn in as Minister for Finance and Public Works Departments in Jayalalitha's government. He became the Chief Minister for the third time when J Jayalalitha passed away on 16 December after a prolonged illness.