Marumalarchi Dravida Munnetra Kazhagam (MDMK) leader Vaiko, who was elected to Rajya Sabha from Tamil Nadu, took oath as the member of the Upper House on Thursday.
The 75-year-old is currently the General Secretary of MDMK. He was a candidate of the DMK for the elections to Rajya Sabha from Tamil Nadu this month.
Vaiko makes a re-entry into the Upper House after 23 years. This will be his fourth term as member of the Council of States.
He had also been elected to the 12th and 13th Lok Sabha from Sivakasi Parliamentary constituency.
Earlier there were speculations over the validity of Vaiko's nomination to Rajya Sabha after he was convicted in a sedition case by a Chennai court.
Later, his nomination was declared valid as he had received a punishment of one year in the sedition case.
Under the Representation of the People Act, a person convicted and sentenced to imprisonment term of two years and more is disqualified from contesting elections.