| Election Name: | 2021 Southend-on-Sea Borough Council |
| Country: | Essex |
| Type: | parliamentary |
| Previous Election: | 2019 Southend-on-Sea Borough Council election |
| Previous Year: | 2019 |
| Election Date: | 6 May 2021 |
| Next Election: | 2022 Southend-on-Sea Borough Council election |
| Next Year: | 2022 |
| Seats For Election: | 17 out of 51 seats to Southend-on-Sea Borough Council |
| Majority Seats: | 26 |
| Turnout: | ? |
| Image1: | File:Cllr Tony Cox (51193361428) (cropped).jpg |
| Leader1: | Tony Cox |
| Party1: | Conservative Party (UK) |
| Leader Since1: | 9 May 2019 |
| Last Election1: | 20 seats, 27.0% |
| Leaders Seat1: | West Shoebury |
| Seats Before1: | 20 |
| Seats1: | 11 |
| Seats After1: | 23 |
| Seat Change1: | 3 |
| Popular Vote1: | 19,569 |
| Percentage1: | 40.5% |
| Swing1: | 13.5% |
| Leader2: | Ian Gilbert |
| Party2: | Labour Party (UK) |
| Leader Since2: | Oct/Nov 2010 |
| Leaders Seat2: | Victoria |
| Last Election2: | 14 seats, 20.8% |
| Seats Before2: | 12 |
| Seats2: | 6 |
| Seats After2: | 13 |
| Seat Change2: | 1 |
| Popular Vote2: | 12,613 |
| Percentage2: | 26.1% |
| Swing2: | 5.3% |
| Image3: | Ind |
| Leader3: | n/a |
| Party3: | Independent politician |
| Leader Since3: | n/a |
| Leaders Seat3: | n/a |
| Last Election3: | 12 seats, 24.2% |
| Seats Before3: | 14 |
| Seats3: | 1 |
| Seats After3: | 10 |
| Seat Change3: | 2 |
| Popular Vote3: | 6,299 |
| Percentage3: | 13.0% |
| Swing3: | 11.2% |
| Image4: | File:Carole Mulroney (cropped).jpg |
| Leader4: | Carole Mulroney |
| Party4: | Liberal Democrats (UK) |
| Leader Since4: | May 2017 |
| Leaders Seat4: | Leigh |
| Last Election4: | 5 seats, 14.1% |
| Seats Before4: | 5 |
| Seats4: | 1 |
| Seats After4: | 5 |
| Popular Vote4: | 5,493 |
| Percentage4: | 11.4% |
| Swing4: | 2.7% |
| Image5: | Green |
| Leader5: | n/a |
| Party5: | Green Party of England and Wales |
| Leader Since5: | n/a |
| Leaders Seat5: | n/a |
| Last Election5: | 0 seats, 7.5% |
| Seats Before5: | 0 |
| Seats5: | 0 |
| Seats After5: | 0 |
| Popular Vote5: | 3,918 |
| Percentage5: | 8.1% |
| Swing5: | 0.6% |
| Leader | |
| Posttitle: | Leader after election |
| Before Election: | Ian Gilbert Labour |
| Before Party: | No overall control |
| After Election: | Ian Gilbert Labour |
| After Party: | No overall control |
Elections to Southend-on-Sea Borough Council took place on 6 May 2021. This was on the same day as other local elections across the United Kingdom.[1] The results saw the Conservatives and Labour pick up seats at the expense of the local Independents.[2]
The council is elected by thirds, so a single member was elected from all 17 wards to a term of four years. The seats elected at this election were last contested in 2016, however due to the COVID-19 pandemic the 2020 elections were delayed for 12 months.[3]
The "rainbow coalition" between Labour, the Liberal Democrats and local independents continued in office, with Labour councillor Ian Gilbert being elected leader of the council.[4] [5]
Directly after the 2019 election the composition of the council was:
| 14 | 5 | 12 | 20 | |
| Labour | Lib Dem | Ind | Conservative |
Prior to the election the composition of the council was:
| 12 | 5 | 14 | 20 | |
| Labour | Lib Dem | Ind | Conservative |
After the election, the composition of the council was:
| 13 | 5 | 10 | 23 | |
| Labour | Lib Dem | Ind | Conservative |
No UKIP candidate as previous (-11.5).
No Independent candidate as previous (-12.0).
No Independent candidate as previous (-14.1).
No UKIP candidate as previous (-11.1).