Vaiko was convicted for sedition over a controversial speech he made in 2009 at the launch of his book.
Tamil politician V Gopalaswamy or Vaiko today filed his nomination for Rajya Sabha polls, a day after the MDMK chief was sentenced to a year in jail for sedition by a Chennai court.
Mr Vaiko filed his nomination in the presence of DMK chief MK Stalin and his lawmakers TR Baalu, Dayanidhi Maran and Kanimozhi. The election to Rajya Sabha seats will be held on July 18, as the term of six members comes to an end on July 24.
Although MDMK has no legislators in the Tamil Nadu assembly, the party was offered a Rajya Sabha seat by the DMK as part of an alliance deal made ahead of the general election earlier this year. The DMK-led alliance won 37 of the 38 Lok Sabha seats in Tamil Nadu.
Both the ruling AIADMK and the main opposition DMK have enough members in the assembly to elect three candidates each. Apart from Mr Vaiko, the DMK nominated M Shanmugam and senior advocate P Wilson.
The MDMK chief was convicted for sedition over a controversial speech he made in 2009 at the launch of his book. The court, however, stayed the execution of the sentence for a month on his application, giving him time to appeal the ruling.
"India will not remain one country if the war against the LTTE in Sri Lanka is not stopped," Mr Vaiko had said during the launch of his book "Naan Kuttram Saatugiren... (I accuse...)." He was charged with speaking against India's sovereignty. The case was, ironically, filed under the DMK-led government.
Sources in his party said that sedition is not among the list of convictions that would instantly disqualify him for contesting the Rajya Sabha polls.
"A two-year jail term alone in other cases would disqualify a lawmaker or a candidate" said DMK Spokesperson A Saravanan.
If elected, the 75-year-old would return to the parliament after 15 years and to the upper house after 23 years. Mr Vaiko spent much of his political life with the DMK. He was a trusted lieutenant of late DMK Chief Karunanidhi and served three terms in Rajya Sabha -- from 1978 to 1996. Seen as a challenger to MK Stalin, who was later groomed as Karunanidhi's heir apparent, Mr Vaiko was expelled from the party in 1993. He was elected to the Lok Sabha twice from Sivakasi. His last tenure was from 1999 to 2004.
Mr Vaiko, an advocate and a powerful speaker in English and Tamil, was arrested by the J Jayalalithaa-led AIADMK government in 2002 under the anti-terror Prevention of Terrorism Act (POTA) for a controversial speech in support of the banned LTTE. He spent 18 months in the Vellore prison. In 2014, the case against him was withdrawn.