| Rank | Heat | Nation | Athletes | Time | Notes |
| 1 | 2 |  Italy | Edoardo Scotti (M), Giancarla Trevisan (W), Alice Mangione (W), Davide Re (M) | 3:16.52 | Q WL, OG*, WC* |
| 2 | 3 |  Brazil | Anderson Henriques (M), Tiffani Marinho (W), Geisa Coutinho (W), Alison dos Santos (M) | 3:16.53 | Q SB, WC* |
| 3 | 3 |  Dominican Republic | Yancarlos Martínez (M), Anabel Medina (W), Marileidy Paulino (W), Alexander Ogando (M) | 3:16.67 | Q PB, OG*, WC* |
| 4 | 3 |  Ireland | Christopher O'Donnell (M), Phil Healy (W), Sharlene Mawdsley (W), Thomas Barr (M) | 3:16.84 | q PB, OG*, WC* |
| 5 | 2 |  Belgium | Jonathan Sacoor (M), Cynthia Bolingo (W), Camille Laus (W), Kevin Borlée (M) | 3:17.23 | Q SB, WC* |
| 6 | 3 |  United Kingdom | Rabah Yousif (M), Laviai Nielsen (W), Emily Diamond (W), Lee Thompson (M) | 3:17.27 | q SB, WC* |
| 7 | 2 |  Colombia | Jhon Perlaza (M), Rosa Escobar (W), Jennifer Padilla (W), Anthony Zambrano (M) | 3:17.61 | PB, WC* |
| 8 | 2 |  Poland | Mateusz Rzeźniczak (M), Aleksandra Gaworska (W), Karolina Łozowska (W), Patryk Grzegorzewicz (M) | 3:17.92 | SB, WC* |
| 9 | 1 |  Netherlands | Nout Wardenburg (M), Femke Bol (W), Lieke Klaver (W), Tony van Diepen (M) | 3:18.04 | Q PB, OG*, WC* |
| 10 | 2 |  Japan | Kosuke Ikeda (M), Nanako Matsumoto (W), Mayu Kobayashi (W), Aoto Suzuki (M) | 3:18.76 | PB, WC* |
| 11 | 1 |  Spain | Julio Arenas (M), Andrea Jiménez (W), Aauri Lorena Bokesa (W), Bernat Erta (M) | 3:18.98 | Q NR, OG*, WC* |
| 12 | 2 |  South Africa | Ukona Khuzwayo (M), Dalene Mpiti (W), Taylon Bieldt (W), Ranti Dikgale (M) | 3:19.18 | PB, WC* |
| 13 | 3 |  Germany | Henrik Krause (M), Luna Thiel (W), Hannah Mergenthaler (W), Johannes Trefz (M) | 3:19.19 | SB |
| 14 | 2 |  Slovakia | Oliver Murcko (M), Iveta Putalová (W), Emma Zapletalová (W), Šimon Bujna (M) | 3:19.66 | PB |
| 15 | 3 |  Belarus | Aliaksandr Vasileuskiy (M), Aliaksandra Khilmanovich (W), Asteria Limai (W), Ihar Zubko [no] (M) | 3:19.73 | PB |
| 16 | 1 |  France | Amandine Brossier (W), Elise Trynkler (W), Christopher Naliali (M), Thomas Jordier (M) | 3:20.95 | SB |
| 17 | 3 |  Botswana | Zibane Ngozi (M), Oarabile Mokenane (W), Christine Botlogetswe (W), Bayapo Ndori (M) | 3:20.97 | SB |
| 18 | 1 |  Turkey | Kubilay Ençü (M), Büşra Yıldırım (W), Elif Polat (W), Sinan Ören (M) | 3:20.98 | SB |
| 19 | 1 |  Czech Republic | Matěj Krsek (M), Barbora Malíková (W), Lada Vondrová (W), Daniel Lehar (M) | 3:21.05 | SB |
| 20 | 1 |  Portugal | Vera Barbosa (W), Ricardo dos Santos (M), Cátia Azevedo (W), Mauro Pereira (M) | 3:21.51 | SB |
| 1 |  Kenya | Jared Momanyi (M), Joan Cherono [de] (W), Mary Moraa (W), Aron Koech (M) | DQ | |
United States
Bahamas
