# 2018 FINA World Swimming Championships (25 m) – Women's 4 × 100 metre medley relay

The women's 4 × 100 metre medley relay competition of the 2018 FINA World Swimming Championships (25 m) was held on 16 December 2018.

## Records

Prior to the competition, the existing world and championship records were as follows.
| | Nation | Time | Location | Date |
| World record | United States | 3:45.20 | Indianapolis, United States | 11 December 2015 |
| Championship record | United States | 3:47.89 | Windsor, Canada | 11 December 2016 |

## Results
### Heats

The heats were started at 10:20.
| Rank | Heat | Lane | Nation | Swimmers | Time | Notes |
| 1 | 2 | 5 | United States | Kathleen Baker (56.96) Melanie Margalis (1:04.85) Kendyl Stewart (56.29) Lia Neal (52.63) | 3:50.73 | Q |
| 2 | 2 | 4 | China | Fu Yuanhui (57.71) Shi Jinglin (1:05.07) Wang Yichun (56.26) Yang Junxuan (52.54) | 3:51.58 | Q |
| 3 | 1 | 4 | Australia | Minna Atherton (57.38) Jessica Hansen (1:05.28) Emily Seebohm (57.51) Ariarne Titmus (52.92) | 3:53.09 | Q |
| 4 | 1 | 3 | Italy | Margherita Panziera (57.63) Martina Carraro (1:05.32) Ilaria Bianchi (57.78) Federica Pellegrini (53.16) | 3:53.89 | Q |
| 5 | 2 | 3 | Japan | Emi Moronuki (57.44) Kanako Watanabe (1:06.52) Yukina Hirayama (57.81) Tomomi Aoki (53.31) | 3:55.08 | Q |
| 6 | 1 | 5 | Russia | Daria Ustinova (58.27) Vitalina Simonova (1:05.46) Daria Kartashova (57.61) Veronika Andrusenko (53.77) | 3:55.11 | Q |
| 7 | 1 | 1 | Germany | Laura Riedemann (58.40) Jessica Steiger (1:06.46) Aliena Schmidtke (58.52) Marie Pietruschka (53.92) | 3:57.30 | Q |
| 8 | 2 | 2 | Canada | Ingrid Wilm (58.55) Sophie Angus (1:06.46) Haley Black (56.49) Aela Janvier (55.97) | 3:57.47 | Q |
| 9 | 1 | 6 | Turkey | Ekaterina Avramova (59.88) Viktoriya Zeynep Güneş (1:07.59) Nida Eliz Üstündağ (58.35) Selen Özbilen (54.66) | 4:00.48 | |
| 10 | 2 | 8 | Switzerland | Seraina Sturzenegger (1:00.93) Lisa Mamie (1:06.79) Svenja Stoffel (58.47) Alexandra Touretski (54.47) | 4:00.66 | |
| 11 | 2 | 7 | Slovakia | Karolina Hájková (59.76) Andrea Podmaníková (1:07.54) Tamara Potocká (59.67) Barbora Mikuskova (55.39) | 4:02.36 | |
| 12 | 2 | 1 | Austria | Caroline Pilhatsch (59.49) Cornelia Pammer (1:07.84) Lena Kreundl (1:00.21) Marlene Kahler (55.29) | 4:02.83 | |
| 13 | 1 | 2 | New Zealand | Emma Godwin (59.22) Ciara Smith (1:09.14) Vanessa Ouwehand (1:01.82) Paige Flynn (54.20) | 4:04.38 | |
| 14 | 2 | 6 | Hong Kong | Wong Toto Kwan To (1:00.09) Kan Cheuk Tung Natalie (1:10.17) Chan Kin Lok (1:00.70) Sze Hang Yu (55.07) | 4:06.03 | |
| 15 | 1 | 7 | Chinese Taipei | Chen Szu-an (1:03.67) Lin Pei-wun (1:10.85) Huang Mei-chien (1:02.93) Wang Wan-chen (58.32) | 4:15.77 | |

### Final

The final was held at 20:00.
| Rank | Lane | Nation | Swimmers | Time | Notes |
| | 4 | United States | Olivia Smoliga (55.86) Katie Meili (1:03.52) Kelsi Dahlia (54.89) Mallory Comerford (51.31) | 3:45.58 | CR |
| | 5 | China | Fu Yuanhui (56.86) Shi Jinglin (1:03.97) Zhang Yufei (56.21) Zhu Menghui (51.76) | 3:48.80 | |
| | 6 | Italy | Margherita Panziera (58.39) Martina Carraro (1:04.47) Elena Di Liddo (56.41) Federica Pellegrini (52.11) | 3:51.38 | |
| 4 | 2 | Japan | Emi Moronuki (57.32) Kanako Watanabe (1:05.58) Ai Soma (56.27) Tomomi Aoki (52.64) | 3:51.81 | |
| 5 | 7 | Russia | Anastasia Fesikova (57.73) Maria Temnikova (1:06.53) Svetlana Chimrova (56.90) Maria Kameneva (52.57) | 3:53.73 | |
| 6 | 1 | Germany | Laura Riedemann (58.04) Jessica Steiger (1:05.80) Aliena Schmidtke (57.41) Annika Bruhn (52.90) | 3:54.15 | |
| 7 | 8 | Canada | Ingrid Wilm (58.63) Sophie Angus (1:06.23) Haley Black (57.08) Aela Janvier (56.10) | 3:58.04 | |
| | 3 | Australia | Minna Atherton (56.91) Jessica Hansen (1:04.08) Emily Seebohm Ariarne Titmus | DSQ | |