Catford South by-election
Results of the by-election held in Catford South ward on Thursday 6 May 2021.
| Candidate | Party | Votes | Status |
| BARKER Matt | The Green Party | 590 | Not elected |
| CASHIN Diana Averil | Liberal Democrats | 891 | Not elected |
| GALLOWAY Richard Paul | Young People’s Party YPP | 52 | Not elected |
| MARTIN Maureen Maud | Christian Peoples Alliance | 114 | Not elected |
| OBI Favour | Conservatives | 761 | Not elected |
| ROYSTON James William | Labour and Co-operative Party | 2,473 | Elected |
| Reason for rejected ballot paper | Number of ballot papers rejected |
| Want of an official mark | 0 |
| Voting for more candidates than the voter was entitled to | 9 |
| Writing or mark by which the voter could be identified | 0 |
| Unmarked or void for uncertainty | 47 |
| Total | 56 |
| Total eligible electorate | Ballot papers received (including rejected votes) | Turnout (%) |
| 11,058 | 4,937 | 44.65 |