In November, Mr Dhinakaran had lost the two-leaves election symbol to a faction of Tamil Nadu's ruling party led by O Panneerselvam and E Palaniswami, after the Election Commission recognised them as the "real" party.
Mr Dhinakaran, nephew of jailed VK Sasikala, will now have to use the pressure cooker symbol for the make-or-break by-election in Chennai's RK Nagar assembly seat, which was the constituency of the AIADMK's powerful leader J Jayalalithaa, who died as chief minister in December last year.
Chief Minister E Palaniswami and his team need the RK Nagar seat to prove that they are in control and that people regard them as inheritors of Ms Jayalalithaa's legacy. The party has fielded a senior leader, E Madhusudanan, who has held the seat before and has influence among Telugu people who have a sizeable presence in RK Nagar. Mr Dhinakaran is also looking to take RK Nagar for the same reason.
The DMK has fielded Marudhu Ganesh, an RK Nagar local who is seen by many as the frontrunner for the seat in the December 21 by-election.
Mr Dhinakaran was sidelined along with his jailed aunt after Mr Panneerselvam and Mr Palaniswami decided to merge in August, after months of hard negotiations and several false starts. "The burden in my heart is gone. No one can separate us, we are children of Amma (Jayalalithaa), and we are brothers," Mr Panneerselvam had said just after the merger.
The sidelined leader had then fought hard for the two-leaves symbol and also control of the party. Mr Dhinakaran was the de facto head of the Mr Palaniswami faction before the latter reunited with Mr O Panneerselvam's faction.
Earlier this year, following allegations of large-scale bribery of voters, the RK Nagar by-election was cancelled and now would be held on December 21.
Mr Dhinakaran was arrested for allegedly trying to bribe Election Commission officials to keep the two-leaves symbol. He is out on bail.