The legislator's reply to the show cause notice sent by the party, when he was suspended on August 5 for violating party discipline and bringing disrepute, was 'unacceptable,' the party said.
"The reply he gave was unacceptable and hence he is dismissed from the primary membership of the party and all his posts," DMK President M K Stalin said in a release adding the removal was a disciplinary action.
Asked on his dismissal from the DMK, Selvam told PTI that he would consult his lawyers adding he would air his views later.
Recently, Selvam praised Prime Minister Narendra Modi and metsaffron party chief J P Nadda in Delhi. Virtually embracing the BJP, the MLA who was formerly the DMK headquarters office secretary and executive committee member had asked people to join the saffron party.
The MLA had also visited the BJP headquarters 'Kamalalayam' here and alleged "family politics" in the DMK. He had said he was not considered for the west district secretary position in the city despite working for the DMK for over two decades and demanded "intra party elections".
Selvam was with the Janaki faction of the AIADMK in the late 1980's following the death of AIADMK founder and then Chief Minister M G Ramachandran in 1987. Former DMK leader and Tamil Nadu Assembly Deputy Speaker V P Duraisamy was another Dravidian party personality who had joined the Saffron party lately.