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

The Women's 400 metre individual medley competition of the 2021 FINA World Swimming Championships (25 m) was held on 16 December 2021.

## Records

Prior to the competition, the existing world and championship records were as follows.

| World record | Mireia Belmonte (ESP) | 4:18.94 | Eindhoven, Netherlands | 12 August 2017 |
| - | - | - | - | - |
| Competition record | Mireia Belmonte (ESP) | 4:19.86 | Doha, Qatar | 3 December 2014 |

## Results

### Heats

The heats were started at 11:10.

| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| - | - | - | - | - | - | - |
| 1 | 4 | 3 | Ilaria Cusinato | Italy | 4:30.27 | Q |
| 2 | 4 | 5 | Tessa Cieplucha | Canada | 4:30.62 | Q |
| 3 | 4 | 4 | Melanie Margalis | United States | 4:30.75 | Q |
| 4 | 3 | 9 | Ellen Walshe | Ireland | 4:30.78 | Q |
| 5 | 3 | 4 | Bailey Andison | Canada | 4:31.08 | Q |
| 6 | 3 | 5 | Zsuzsanna Jakabos | Hungary | 4:32.02 | Q |
| 7 | 3 | 3 | Katie Shanahan | Great Britain | 4:32.75 | Q |
| 8 | 3 | 6 | Emma Weyant | United States | 4:32.97 | Q |
| 9 | 3 | 0 | Yu Yiting | China | 4:33.29 | |
| 10 | 2 | 4 | Anja Crevar | Serbia | 4:33.30 | |
| 11 | 3 | 2 | Viktoriya Zeynep Güneş | Turkey | 4:34.42 | |
| 12 | 4 | 1 | Viktória Mihályvári-Farkas | Hungary | 4:35.69 | |
| 13 | 4 | 7 | Catalina Corró | Spain | 4:35.74 | |
| 14 | 4 | 8 | Nathalia Almeida | Brazil | 4:36.22 | |
| 15 | 4 | 2 | Maria Ugolkova | Switzerland | 4:37.75 | |
| 16 | 4 | 6 | Anastasiia Sorokina | Russian Swimming Federation | 4:38.49 | |
| 17 | 3 | 8 | Jung Hae-un | South Korea | 4:39.53 | |
| 18 | 4 | 0 | Nikoleta Trníková | Slovakia | 4:39.77 | |
| 19 | 2 | 3 | Jimena Pérez | Spain | 4:39.88 | |
| 20 | 3 | 7 | Kristýna Horská | Czech Republic | 4:39.90 | |
| 21 | 3 | 1 | Deniz Ertan | Turkey | 4:40.39 | |
| 22 | 1 | 4 | Kristen Romano | Puerto Rico | 4:41.84 | NR |
| 23 | 2 | 5 | Jinjutha Pholjamjumrus | Thailand | 4:42.18 | |
| 24 | 4 | 9 | Claudia Hufnagl | Austria | 4:42.64 | |
| 25 | 2 | 6 | Chloe Cheng | Hong Kong | 4:44.53 | |
| 26 | 2 | 1 | Florencia Perotti | Argentina | 4:46.31 | |
| 27 | 2 | 9 | Iman Avdić | Bosnia and Herzegovina | 4:47.42 | |
| 28 | 2 | 2 | Alexandra Dobrin | Romania | 4:47.99 | |
| 29 | 2 | 0 | Maria Romanjuk | Estonia | 4:50.91 | |
| 30 | 1 | 5 | Laura Melo | Colombia | 5:00.25 | |
| 31 | 1 | 6 | Karla Abarca | Nicaragua | 5:08.94 | |
| 32 | 1 | 3 | Samantha van Vuure | Curaçao | 5:13.46 | |
| | 2 | 7 | María Fe Muñoz | Peru | DNS | |
| | 2 | 8 | Ashley Lim | Singapore | DNS | |

### Final

The final was held at 18:49.

| Rank | Lane | Name | Nationality | Time | Notes |
| - | - | - | - | - | - |
| | 5 | Tessa Cieplucha | Canada | 4:25.55 | |
| | 6 | Ellen Walshe | Ireland | 4:26.52 | NR |
| | 3 | Melanie Margalis | United States | 4:26.63 | |
| 4 | 8 | Emma Weyant | United States | 4:27.45 | |
| 5 | 2 | Bailey Andison | Canada | 4:28.97 | |
| 6 | 4 | Ilaria Cusinato | Italy | 4:29.37 | |
| 7 | 7 | Zsuzsanna Jakabos | Hungary | 4:31.49 | |
| 8 | 1 | Katie Shanahan | Great Britain | 4:32.68 | |
