| Final 21:36 | | time | | gap | L | | 1. |  Australia | 3:41.30 | GR | | 4 | 1. | | | Kaylee McKeown 59.01s, Zac Stubblety-Cook 59.52s, Matthew Temple 50.89s Emma McKeon 51.88s, | | 2. |  Canada | 3:43.98 | | | 3 | 2. | | | Kylie Masse 59.11s, James Dergousoff 1:00.57, Maggie Mac Neil 56.50s, Ruslan Gaziev 47.80s, | | 3. |  England | 3:44.03 | | | 5 | 3. | | | Lauren Cox 1:00.81s, James Wilby 58.94s, James Guy 51.19s, Freya Anderson 53.09s | | 4. |  South Africa | 3:44.38 | | | 6 | 4. | | | Pieter Coetze 53.42s, Lara van Niekerk 1:05.41, Chad le Clos 50.94s, Aimee Canny 54.61s, | | 5. |  Wales | 3:47.76 | | | 7 | 5. | | | Medi Harris 59.48s, Kyle Booth 1:01.68, Harriet Jones 58.26s, Matt Richards 48.34s | | 6. |  Scotland | 3:48.55 | | | 2 | 6. | | | Craig McNally 54.50s, Ross Murdoch 59.45s, Keanna Macinnes 59.52s, Lucy Hope 55.08s | | 7. |  Jersey | 4:01.10 | | | 1 | 7. | | | Gemma Atherley 1:04.21, Robbie Jones 1:03.78, Harry Shalamon 55.10s, Lily Scott 58.01s | | 8. |  Guernsey | 4:02.79 | | | 8 | 8. | | | Tatiana Tostevin 1:03.95, Ronny Hallett 1:04.45, Charlie-Joe Hallett 56.14s, Orla Rabey 58.25s |
| 89 Competitors from 17 Nations. | | World and Commonwealth Record" Great Britain (Kathleen Dawson, Adam Peaty. James Guy. Anna Hopkin 3:37.58 Tokyo, Japan 31 July 2021 | | Commonwealth Games Record: New event |
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Heats - Tuesday, 2nd August 11:19 | | Best 8 times advanced to Final. |
| Heat 3 | | time | | gap | L | Rk. | | 1. | Australia | 3:45.34 | Q, GR | | 4 | 1. | | | Mitch Larkin 54.32s, Sam Williamson 1:00.40, Alex Perkins 57.94s, Madison Wilson 52.68s | | 3. | Canada | 3:51.43 | Q | | 5 | 3. | | | Javier Acevedo 54.59s, Sophie Angus 1:08.08, Patrick Hussey 53.44s, Rebecca Smith 55.32s | | 6. | Wales | 3:53.05 | Q | | 3 | 6. | | | Charlotte Evans 1:02.67, Kyle Booth 1:02.00, Harriet Jones 58.54s, Liam White 49.84s | | 7. | Jersey | 4:00.49 | Q | | 6 | 7. | | | Gemma Atherley 1:03.73, Robbie Jones 1:03.86, Harry Shalamon 54.99s, Lily Scott 57.91s | | 8 | Guernsey | 4:04.02 | Q | | 2 | 8. | | | Tatiana Tostevin 1:03.83, Ronny Hallett 1:05.37, Charlie-Joe Hallett 56.49s, Orla Rabey 58.33s | | 12. |  Cook Islands | 4:13.09 | | | 7 | 12. | | | Bede Aitu 1:00.91, Kirsten Fisher-Marsters 1:15.81, Lanihei Connolly 1:05.68, Wesley Roberts 50.69s | | 14. |  Kenya | 4:16.66 | | | 8 | 14. | | | Imara Thorpe 1:08.33, Emily Muteti 1:15.87, Ridhwan Mohamed 58.29s, Monyo Maina 54.17s | | 15. |  Uganda | 4:18.04 | | | 1 | 15. | | | Avice Meya 1:10.68, Tendo Mukalazi 1:08.54, Atuhaire Ambala 59.29s, Kirabo Namutebi 59.53s |
| Heat 2 | | time | | gap | L | Rk. | | 2. | England | 3:51.08 | Q | | 4 | 2. | | | Alicia Wilson 1:02.93, Greg Butler 1:01.45, Edward Mildred 51.58s, Abbie Wood 55.12s | | 4. | South Africa | 3:51.56 | Q | | 5 | 4. | | | Rebecca Meder 1:02.50, Brenden Crawford 1:00.70, Matthew Sates 53.57s, Emma Chelius 54.79s | | 5. | Scotland | 3:52.32 | Q | | 3 | 5. | | | Martyn Walton 55.60s, Archie Goodburn 1:01.60, Tain Bruce 59.80s, Lucy Hope 55.32s | | 9. |  Isle of Man | 4:04.59 | R | | 6 | 9. | | | Emma Hodgson 1:05.93, Laura Kinley 1:10.79, Peter Allen 56.20s, Joel Watterson, 51.67s | | 10. |  Barbados | 4:08.59 | R | | 2 | 10. | | | Danielle Titus 1:05.06, Luis Sebastian Weekes 1:04.84 Adara Stoddard, 1:07.82, Jack Kirby 50.87s | | 11. |  Bahamas | 4:08.80 | | | 8 | 11. | | | Davante Carey 58.96s, Lillian Higgs 1:13.22, Katelyn Cabral 1:05.67, Lamar Taylor, 50.95s | | -. |  Saint Helena | DNS | | | 1 | -. | | -. |  Fiji | DNS | | | 7 | -. |
| Heat 1 | | time | | gap | L | Rk. | | 13. |  Samoa | 4:13.66 | | | 5 | 13. | | | Lushavel Stickland 1:12.25, Brandon Schuster 1:04.33, Olivia Borg 1:01.20, Kokoro Frost 55.88s | | 16. |  Zambia | 4:30.43 | | | 6 | 16. | | | Kumaren Naidu 1:06.81, Zach Moyo 1:12.31, Jade Phiri 1:08.09, Tilka Paljk, 1:03.22 | | 17. |  Maldives | 4:57.22 | | | 4 | 17. | | | Aishath Sausan 1:21.70, Mohamed Aan Hussain 1:16.95, Mubal Azzam Ibrahim, 1:06.09, Hamna Ahmed 1:12.48 | | -. |  Singapore | DNS | | | 3 | -. |
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