After his resignation he became the Public Works Department minister in the Jayalalithaa government. O. Paneerselvam was the leader of the AIADMK legislative party and the Leader of the Opposition in the Tamil Nadu legislative assembly for about two weeks, after the party lost the assembly elections in May 2006. After all the AIADMK legislators were suspended by the speaker of the house, Jayalalithaa who had decided not to attend the Legislative Assembly decided to return and replaced O. Paneerselvam as the Leader of the Opposition.
He has been twice elected to the Tamil Nadu assembly from Periyakulam constituency. His confidants affectionately call him with his initials as 'OP'. He is the only CM after Kamaraj and Bakthavatsalam era who has not faced any corruption charges and was commended as Mr. Clean even when he was a Minister even by his political opponents.
| Preceded by: J. Jayalalithaa | Chief Ministers of Tamil Nadu | Followed by: J. Jayalalithaa |