A total of 3,998 candidates are fighting it out to enter the 234-member Tamil Nadu assembly.
As per the Election Commission of India, 72.81 per cent of the 6.29 crore voters have cast their votes in the poll.
Apart from the Assembly election results, the bypoll results for the Kanniyakumari Lok Sabha constituency will also be known on Sunday.
The bypoll was fought mainly between former Union Minister and BJP's Pon Radhakrishnan and Congress candidate Vijay Vasanth, son of late MP H. Vasanth Kumar.
The assembly poll results will be crucial for the ruling AIADMK government led by Chief Minister K. Palaniswami and the principal opposition party DMK led by M.K. Stalin.
Majority of the pre-poll opinion survey and the exit polls predicted a large win for the 10 year power starved DMK.
While counting would begin at 8 a.m., by noon the trend will be known as to who would storm the Fort St. George, the seat of power in Tamil Nadu.
Counting of votes will be at 75 centres in the state with the deployment of state police and central para military forces for security.
Vote counting will be videographed.
With the spread of coronavirus, counting agents and others will be allowed into the counting centres on the production of Covid-19 negative test report or should have been vaccinated twice.
Though it was a five cornered contest, the major rivals are the ruling AIADMK-led alliance and the DMK-led front.
The other players in the fray are actor-turned-politicians Kamal Haasan's Makkal Needhi Maiam (MNM) alliance, the alliance led by Amma Makkal Munnetra Kazhagam (AMMK) floated by T.T.V. Dhinakaran and movie director Seeman's Naam Tamilar Katchi (NTK).
The ruling AIADMK fought in 179 seats and six other small parties each contesting in one seat under the former's Two Leaves symbol.
The others in the AIADMK alliance are the BJP (contested in 20 seats) and PMK (23), TMC (6).
The DMK contested in 173 seats while alliance parties Congress (25), CPI, CPI-M, MDMK and VCK in six seats each, IUML, KMDK (3 each), MMK (2), All India Forward Bloc, Makkal Viduthalai Katchi, Athi Thamizhar Peravai and Tamizhaga Vazhuvurimai Katchi each contesting in one seat.
A total of 187 candidates -- DMK's own and that of alliance parties -- contested under the former's Rising Sun symbol.
The MNM allied with actor Sarathkumar's AISMK and IJK while Dhinakaran's AMMK allied with the DMDK, AIMIM and others.
The Seeman-led NTK went alone contesting in all the 234 constituencies and fielding 50 per cent women candidates.
The other parties in the fray on their own are the Bahujan Samaj Party (contesting in 160 seats), Puthiya Tamizhagam (60 seats) and Republican Party of India (16 seats).
Notable candidates in the polls and the constituencies are: Palaniswami (Edappadi), Deputy Chief Minister O. Panneerselvam (Bodinayakkanur), Stalin (Kolathur), his son Udhayanidhi Stalin (Chepauk-Tiruvallikeni), DMDK Treasurer and Vijayakant's wife Premalatha (Vridhachalam), MNM founder Kamal Haasan (Coimbatore South), TN BJP President L. Murugan (Dharapuram), actor Khushbu Sundar (Thousand Lights), TN BJP Vice President K.Annamalai (Aravakurichi), PMK's G.K.Mani (Pennagaram) and Seeman (Tiruvottriyur).
In the neighbouring Puducherry, Union Territory having just over 10 lakh voters, the fight for the 30-member Assembly was majorly between the Congress led United Progressive Alliance (UPA) consisting of Congress, DMK, CPI, VCK and an Independent and the National Democratic Alliance (NDA) comprising of All India N.R. Congress, BJP and AIADMK.
The voter turnout was 81.69 per cent.
The exit polls have predicted a victory for NDA in Puducherry.