"The party General Secretary V K Sasikala will select the candidate and announce the name," he said.
The seat had fallen vacant after the death of former Chief Minister J Jayalalithaa.
Mr Dhinkaran, who was speaking at a function in Tiruchirappalli, urged all factions of AIADMK to accept Sasikala's leadership and work under her.
He also welcomed Lok Sabha Deputy Speaker and AIADMK leader M Thambidurai reported remarks to the factions to work for AIADMKs victory in RK Nagar.
Mr Dhinakaran was speaking after participating in a function here to distribute Nilavembu kudineer (herbal drink) to fight dengue.
The K Palaniswami led government and Mr Dhinakaran are engaged in a tussle for power, with the latter accusing the Chief Minister of "betraying" Sasikala who had nominated him to the top post in February following a revolt by then rebel leader Mr Panneerselvam.
Mr Panneerselvam had since merged his faction with that of Mr Palaniswami and is now Deputy Chief Minister in the cabinet.
Mr Dhinakaran had met the then Governor Ch Vidyasagar Rao and sought removal of Mr Palaniswami as Chief Minister.
In August, 19 MLAs supporting him had met Mr Rao and pressed for a similar demand, saying they had lost confidence in him.
However, one of the MLAs had switched over to the Chief Minister's camp later.
The Election Commission had on Thursday ordered Tamil Nadu government to conduct the by-poll before December 31.
Last month, Madras High Court had ordered the EC to hold the election at the earliest, preferably before December 31.