# 2021 FINA World Swimming Championships (25 m) – Women's 400 metre freestyle

The Women's 400 metre freestyle competition of the 2021 FINA World Swimming Championships (25 m) was held on 19 December 2021.

## Records

Prior to the competition, the existing world and championship records were as follows.
| World record | Ariarne Titmus (AUS) | 3:53.92 | Hangzhou, China | 14 December 2018 |
| Competition record | Ariarne Titmus (AUS) | 3:53.92 | Hangzhou, China | 14 December 2018 |

## Results
### Heats

The heats were started at 10:14.
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 5 | 7 | Li Bingjie | China | 4:01.26 | Q |
| 2 | 5 | 5 | Anastasiya Kirpichnikova | Russian Swimming Federation | 4:01.35 | Q |
| 3 | 5 | 4 | Summer McIntosh | Canada | 4:01.82 | Q |
| 4 | 4 | 4 | Siobhán Haughey | Hong Kong | 4:02.57 | Q |
| 5 | 5 | 2 | Anna Egorova | Russian Swimming Federation | 4:02.66 | Q |
| 6 | 4 | 7 | Paige Madden | United States | 4:03.03 | Q |
| 7 | 4 | 3 | Isabel Marie Gose | Germany | 4:03.13 | Q |
| 8 | 3 | 5 | Joanna Evans | Bahamas | 4:03.58 | Q |
| 9 | 5 | 6 | Ajna Késely | Hungary | 4:03.84 | |
| 10 | 4 | 5 | Simona Quadarella | Italy | 4:03.93 | |
| 11 | 4 | 2 | Freya Anderson | Great Britain | 4:03.94 | |
| 12 | 5 | 0 | Nathalia Almeida | Brazil | 4:06.13 | |
| 13 | 3 | 2 | Emma Weyant | United States | 4:06.71 | |
| 14 | 5 | 1 | Martina Caramignoli | Italy | 4:06.89 | |
| 15 | 5 | 8 | Merve Tuncel | Turkey | 4:07.39 | |
| 16 | 2 | 1 | Anja Crevar | Serbia | 4:07.49 | NR |
| 17 | 5 | 9 | Han Da-kyung | South Korea | 4:08.52 | |
| 18 | 3 | 9 | Elisbet Gámez | Cuba | 4:09.08 | |
| 19 | 4 | 1 | Beril Böcekler | Turkey | 4:09.16 | |
| 20 | 4 | 6 | Valentine Dumont | Belgium | 4:09.35 | |
| 21 | 4 | 0 | Leonie Kullmann | Germany | 4:09.41 | |
| 22 | 5 | 3 | Charlotte Bonnet | France | 4:10.10 | |
| 23 | 4 | 8 | Gabrielle Roncatto | Brazil | 4:10.34 | |
| 24 | 3 | 7 | Monique Olivier | Luxembourg | 4:10.57 | |
| 25 | 3 | 4 | Ryu Ji-won | South Korea | 4:11.06 | |
| 26 | 3 | 1 | Lena Opatril | Austria | 4:11.95 | |
| 27 | 2 | 2 | Zhanet Angelova | Bulgaria | 4:12.58 | |
| 27 | 4 | 9 | Diana Durães | Portugal | 4:12.58 | |
| 29 | 2 | 4 | María de Valdés | Spain | 4:12.86 | |
| 30 | 3 | 6 | Laura Lahtinen | Finland | 4:16.77 | |
| 31 | 3 | 0 | Michaela Pulford | South Africa | 4:17.27 | |
| 32 | 2 | 5 | Delfina Dini | Argentina | 4:17.51 | |
| 33 | 1 | 5 | Daniela Alfaro | Costa Rica | 4:18.79 | |
| 34 | 2 | 3 | Iman Avdić | Bosnia and Herzegovina | 4:19.54 | |
| 35 | 2 | 0 | Arianna Valloni | San Marino | 4:21.54 | |
| 36 | 2 | 7 | Sasha Gatt | Malta | 4:21.65 | |
| 36 | 3 | 8 | Matea Sumajstorčić | Croatia | 4:21.65 | |
| 38 | 2 | 8 | Eva Petrovska | North Macedonia | 4:26.38 | |
| 39 | 1 | 6 | Natalia Kuipers | United States Virgin Islands | 4:26.48 | |
| 40 | 2 | 9 | Fatima Alkaramova | Azerbaijan | 4:29.12 | |
| 41 | 1 | 4 | Michell Ramírez | Honduras | 4:31.26 | |
| 42 | 1 | 2 | Katie Rock | Albania | 4:35.55 | |
| 43 | 1 | 7 | Alexia Savinova | Moldova | 4:37.13 | |
| 44 | 1 | 1 | Bianca Mitchell | Antigua and Barbuda | 4:37.56 | |
| 45 | 1 | 8 | Keana Santos | Guam | 5:04.07 | |
| | 1 | 3 | Talita Te Flan | Ivory Coast | DNS | |
| | 2 | 6 | Sabína Kupčová | Slovakia | DNS | |
| | 3 | 3 | Quah Jing Wen | Singapore | DNS | |

### Final

The final was held at 18:49.
| Rank | Lane | Name | Nationality | Time |
| | 4 | Li Bingjie | China | 3:55.83 |
| | 3 | Summer McIntosh | Canada | 3:57.87 |
| | 6 | Siobhán Haughey | Hong Kong | 3:58.12 |
| 4 | 5 | Anastasiya Kirpichnikova | Russian Swimming Federation | 3:58.56 |
| 5 | 7 | Paige Madden | United States | 3:59.58 |
| 6 | 1 | Isabel Marie Gose | Germany | 4:00.82 |
| 7 | 8 | Joanna Evans | Bahamas | 4:01.09 |
| 8 | 2 | Anna Egorova | Russian Swimming Federation | 4:02.11 |