| Rank | Heat | Nation | Athletes | Time | Notes |
| 1 | 3 |  Poland | Kajetan Duszyński (M), Patrycja Wyciszkiewicz (W), Justyna Święty-Ersetic (W), Karol Zalewski (M) | 3:15.46 | Q, WL, AR, *WC |
| 2 | 3 |  United States | Brionna Thomas (W), My'Lik Kerley (M), Olivia Baker (W), Dontavius Wright (M) | 3:16.01 | Q, SB, *WC |
| 3 | 3 |  Italy | Davide Re (M), Giancarla Trevisan (W), Andrew Howe (M), Raphaela Lukudo (W) | 3:16.12 | q, NR*,[3] *WC |
| 4 | 2 |  Canada | Austin Cole (M), Aiyanna Stiverne (W), Alicia Brown (W), Philip Osei (M) | 3:16.78 | Q, NR, *WC |
| 5 | 2 |  Germany | Tobias Lange (M), Laura Müller (W), Nadine Gonska (W), Torben Junker (M) | 3:16.85 | Q, NR, *WC |
| 6 | 2 |  Kenya | Jared Nyambweke Momanyi (M), Maureen Nyatichi Thomas (W), Hellen Syombua (W), Aron Koech (M) | 3:16.90 | q, NR, *WC |
| 7 | 1 |  Belgium | Julien Watrin (M), Camille Laus (W), Liefde Schoemaker (W), Dylan Borlée (M) | 3:18.03 | Q, NR, *WC |
| 8 | 1 |  Brazil | Lucas Carvalho (M), Tiffani Marinho (W), Cristiane Silva (W), Alexander Russo (M) | 3:18.26 | Q, AR, *WC |
| 9 | 1 |  Jamaica | Fitzroy Dunkley (M), Janieve Russell (W), Rhonda Whyte (W), Jamari Rose (M) | 3:18.47 | NR, *WC |
| 10 | 3 |  France | Wilfried Happio (M), Kellya Pauline (W), Estelle Perrossier (W), Nicolas Courbiere (M) | 3:18.93 | NR, *WC |
| 11 | 3 |  Japan | Rikuya Ito (M), Seika Aoyama (W), Mayu Inaoka (W), Naoki Kitadani (M) | 3:19.71 | NR, *WC |
| 12 | 2 |  Great Britain | Alex Haydock-Wilson (M), Finette Agyapong (W), Anyika Onuora (W), Jamal Rhoden-Stevens (M) | 3:20.49 | NR, *WC |
| 13 | 2 |  China | Lu Zhiquan (M), Wang Chunyu (W), Huang Guifen (W), Yu Yang (M) | 3:21.66 | |
| 14 | 1 |  Australia | Ian Halpin (M), Rebecca Bennett (W), Angeline Blackburn (W), Luke Stevens (M) | 3:21.80 | SB |
| 15 | 1 |  India | Jithu Baby (M), Sonia Baishya (W), Prachi (W), Antony Alex (M) | 3:23.59 | |
| 16 | 2 |  Kazakhstan | Andrey Sokolov (M), Svetlana Golendova (W), Elina Mikhina (W), Mikhail Litvin (M) | 3:24.54 | |
| 3 |  Papua New Guinea | Emmanuel Wanga (M), Leonie Beu (W), Shadrick Tansi (M), Isila Manukip Apkup (W) | DQ | R170.19[4] |
| 1 |  South Africa | | DNS | |
United States
Bahamas
