The DMK alliance swept the northern and delta regions and also performed well in the south, while the AIADMK managed to retain seats in its stronghold of western Tamil Nadu with considerable success.
Constituency-wise results of 2016 and 2021 Assembly elections
Constituency-wise map of Tamil Nadu showing the seat share in 2016 Assembly elections.
Constituency-wise map of Tamil Nadu showing the seat share in 2021 Assembly elections.
Tamil Nadu seat share
Poor representation of women
This year saw the lowest representation of women since since 2001.
While 376 women were in the fray, 12 have been elected.
6 from DMK
3 from AIADMK
2 from BJP
1 from Congress
The table shows the performance of key parties in 2021 and 2016
In 2021
| Party | Contested | Won | Total Vote Share (%) | Contested Vote Share (%) |
| Dravida Munnetra Kazhagam | 188 | 133 | 37.7 | 46.45 |
| All India Anna Dravida Munnetra Kazhagam | 191 | 66 | 33.29 | 40.48 |
| Indian National Congress | 25 | 18 | 4.27 | 41.36 |
| Pattali Makkal Katchi | 23 | 5 | 3.8 | 37.61 |
| Bharatiya Janata Party | 20 | 4 | 2.62 | 34.26 |
| Viduthalai Chiruthaigal Katchi | 6 | 4 | 0.99 | 42.44 |
| Communist Party of India (Marxist) | 6 | 2 | 0.85 | 35.17 |
| Communist Party of India | 6 | 2 | 1.09 | 43.28 |
| Naam Tamilar Katchi | 234 | 0 | 6.58 | 6.58 |
| Makkal Needhi Maiam | 180 | 0 | 2.62 | 3.43 |
| Amma Makkal Munnettra Kazagam | 165 | 0 | 2.35 | 3.33 |
| Desiya Murpokku Dravida Kazhagam | 60 | 0 | 0.43 | 1.68 |
In 2016
| Party | Contested | Won | Total Vote Share (%) | Contested Vote Share (%) |
| Dravida Munnetra Kazhagam | 180 | 89 | 31.64 | 41.35 |
| All India Anna Dravida Munnetra Kazhagam | 234 | 136 | 40.77 | 40.77 |
| Indian National Congress | 41 | 8 | 6.42 | 36.74 |
| Pattali Makkal Katchi | 232 | 0 | 5.32 | 5.41 |
| Bharatiya Janata Party | 188 | 0 | 2.84 | 3.57 |
| Viduthalai Chiruthaigal Katchi | 25 | 0 | 0.77 | 6.98 |
| Communist Party of India (Marxist) | 25 | 0 | 0.71 | 6.8 |
| Communist Party of India | 25 | 0 | 0.79 | 7.25 |
| Naam Tamilar Katchi | 231 | 0 | 1.06 | 1.08 |
| Makkal Needhi Maiam | - | - | ||
| Amma Makkal Munnettra Kazagam | - | - | ||
| Desiya Murpokku Dravida Kazhagam | 104 | 0 | 2.39 | 5.42 |
The table shows the constituencies that flipped and the ones that were retained by both the major alliances
| Delta | North | South | West | Total | |
| Retained by AIADMK+ | 3 | 7 | 12 | 33 | 55 |
| Flipped from DMK+ to AIADMK+ | 1 | 5 | 6 | 8 | 20 |
| Retained by DMK+ | 15 | 39 | 20 | 4 | 78 |
| Flipped from AIADMK+ to DMK+ | 22 | 27 | 20 | 12 | 81 |
| Total | 41 | 78 | 58 | 57 | 234 |
District-wise breakdown of winners
North
South
Delta
West
Margins widen
The victory margins widened in the 2021 election compared to 2016
| Margin | (2021) | (2016) |
| < 1000 | 8 | 16 |
| 1000 to 5000 | 31 | 37 |
| 5000 to 10000 | 30 | 44 |
| 10000 to 20000 | 51 | 74 |
| 20000 to 50000 | 89 | 59 |
| > 50000 | 25 | 3 |
25,151 average winning margin for parties in DMK alliance in 2021.
18,044 average winning margin for parties in AIADMK alliance.
I. Periyasamy of DMK won Athoor with the widest margin of 1,35,571 votes.
J. Karunanithi of DMK won T. Nagar with the narrowest margin of 137 votes.
