# 2021 FINA World Swimming Championships (25 m) – Women's 4 × 100 metre medley relay

The Women's 4 × 100 metre medley relay competition of the 2021 FINA World Swimming Championships (25 m) was held on 21 December 2021.

## Records

Prior to the competition, the existing world and championship records were as follows.
| World record | United States (USA) | 3:44.52 | Budapest, Hungary | 21 November 2020 |
| Competition record | United States (USA) | 3:45.58 | Hangzhou, China | 16 December 2018 |

## Results
### Heats

The heats were started at 10:21.
| Rank | Heat | Lane | Nation | Swimmers | Time | Notes |
| 1 | 1 | 5 | Sweden | Hanna Rosvall (57.86) Emelie Fast (1:05.59) Louise Hansson (56.04) Michelle Coleman (53.18) | 3:52.67 | Q |
| 2 | 1 | 4 | Canada | Kylie Masse (56.62) Sydney Pickrem (1:05.46) Katerine Savard (57.41) Summer McIntosh (53.55) | 3:53.04 | Q |
| 3 | 2 | 3 | Italy | Silvia Scalia (57.71) Martina Carraro (1:05.66) Ilaria Bianchi (57.39) Costanza Cocconcelli (52.92) | 3:53.68 | Q |
| 4 | 2 | 4 | United States | Katharine Berkoff (56.62) Kate Douglass (1:05.06) Torri Huske (58.81) Paige Madden (53.24) | 3:53.73 | Q |
| 5 | 1 | 3 | Russian Swimming Federation | Daria Ustinova (59.23) Nika Godun (1:04.46) Daria Klepikova (58.45) Ekaterina Nikonova (53.01) | 3:55.15 | Q |
| 6 | 2 | 6 | Netherlands | Maaike de Waard (57.30) Kim Busch (1:08.74) Tessa Giele (58.66) Marrit Steenbergen (51.98) | 3:56.68 | Q |
| 7 | 2 | 2 | Switzerland | Nina Kost (59.26) Lisa Mamié (1:05.67) Maria Ugolkova (56.98) Alexandra Touretski (54.88) | 3:56.79 | Q, NR |
| 8 | 2 | 5 | China | Wan Letian (57.63) Yu Yiting (1:07.23) Zhu Jiaming (59.39) Cheng Yujie (52.95) | 3:57.20 | Q |
| 9 | 1 | 7 | Turkey | Ekaterina Avramova (58.46) Viktoriya Zeynep Güneş (1:06.07) Nida Eliz Üstündağ (59.22) Selen Özbilen (56.65) | 4:00.40 | |
| 10 | 2 | 7 | South Korea | Kim Seo-yeong (1:00.20) Back Su-yeon (1:07.31) Park Ye-rin (58.32) Jeong So-eun (55.18) | 4:01.01 | |
| 11 | 1 | 1 | Austria | Caroline Pilhatsch (59.44) Cornelia Pammer (1:09.12) Lena Kreundl (59.24) Lena Opatril (55.16) | 4:02.96 | |
| 12 | 1 | 6 | Hong Kong | Stephanie Au (59.50) Lam Hoi Kiu (1:09.44) Natalie Kan (59.80) Katii Tang (55.10) | 4:03.84 | |
| 13 | 2 | 8 | Thailand | Jinjutha Pholjamjumrus (1:02.28) Phiangkhwan Pawapotako (1:10.99) Jenjira Srisaard (59.83) Kornkarnjana Sapianchai (56.09) | 4:09.19 | |
| | 1 | 2 | France | | DNS | |
| | 2 | 1 | Slovakia | | DNS | |

### Final

The final was held at 20:06.
| Rank | Lane | Nation | Swimmers | Time | Notes |
| | 4 | Sweden | Louise Hansson (56.25) Sophie Hansson (1:03.70) Sarah Sjöström (54.65) Michelle Coleman (51.60) | 3:46.20 | ER |
| | 5 | Canada | Kylie Masse (55.76) Sydney Pickrem (1:04.97) Maggie Mac Neil (55.30) Kayla Sanchez (51.33) | 3:47.36 | NR |
| | 8 | China | Peng Xuwei (57.12) Tang Qianting (1:03.25) Zhang Yufei (54.93) Cheng Yujie (52.11) | 3:47.41 | AS |
| 4 | 6 | United States | Katharine Berkoff (56.02) Emily Escobedo (1:04.99) Claire Curzan (55.61) Abbey Weitzeil (51.06) | 3:47.68 | |
| 5 | 2 | Russian Swimming Federation | Maria Kameneva (56.59) Nika Godun (1:04.53) Svetlana Chimrova (56.18) Ekaterina Nikonova (52.64) | 3:49.94 | NR |
| 6 | 3 | Italy | Silvia Scalia (57.56) Martina Carraro (1:04.98) Elena Di Liddo (55.93) Silvia Di Pietro (52.56) | 3:51.03 | NR |
| 7 | 7 | Netherlands | Maaike de Waard (56.64) Kim Busch (1:08.25) Tessa Giele (57.20) Marrit Steenbergen (51.88) | 3:53.97 | NR |
| 8 | 1 | Switzerland | Nina Kost (58.98) Lisa Mamié (1:05.79) Maria Ugolkova (56.35) Alexandra Touretski (54.72) | 3:55.84 | NR |