The PMK leader said that Mathiyan had served 34 years in prison in a case related to the murder of a forest officer and was innocent.
Ramadoss requested Chief Minister Stalin to include Mathiyan in the list of prisoners to be given amnesty on medical grounds as he is suffering from several age-related illnesses.
Stalin had made an announcement in the state assembly under Rule 110 on providing amnesty to 700 convicts to mark the anniversary of Annadurai.
The state Home department has already issued an order framing guidelines for convicts that fall under eligible categories for the amnesty scheme.
Ramadoss in a tweet on Friday said, "It was unjustifiable on the part of the state government for not forthcoming to grant premature release for Mathiyan despite the fact that he spent 34 years behind the bars."
The PMK leader also said that the Madras High Court had asked the government to consider the premature release of Mathiyan.