The opposition DMK had alleged in court that one lakh fake voters have been registered for the election in RK Nagar and it should not be held till corrections are made.
The high court has instructed the Election Commission to hold the bypoll before December 31.
The election for the state legislator or MLA from RK Nagar, which Jayalalithaa represented twice, was to be held in April, but was cancelled after huge wads of cash were found in Chennai.
TTV Dhinakaran, sidelined by the AIADMK after two factions of the party headed by Chief Minister E Palanasamy and O Panneerselvam merged, had said that he would contest the election as the candidate of the ruling AIADMK.
Dhinakaran is the nephew of VK Sasikala, who was Jayalalithaa’s closest aide.
Sasikala is lodged in jail since February in the Rs 66.65 crore disproportionate assets case.