A resolution to this effect was passed at the DMK's general council meeting held here at the party headquarters. Stalin, 63, would have all the powers of a President, the official added.
The meeting was chaired by party's General Secretary K. Anbazhagan as President M. Karunanidhi was advised bed rest.
Stalin would continue as the party's Treasurer.
Referring to Karunanidhi's health, Stalin said he could not say that he was happy given the juncture at which the decision was taken.
"I consider the post of Working President is a responsibility. I will function with responsibility," Stalin said.