Heat 2
dimanche 6 août 2017, 12h55 GMT – 12h55 GMT
| Nom | Équipe | Temps | |
|---|---|---|---|
| 1 |  Shaunae Miller-Uibo | Bahamas | 50.97″ |
| 2 |  Stephenie McPherson | Jamaica | + 0.3″ |
| 3 |  Yinka Ajayi | Nigeria | + 0.61″ |
| 4 |  Bianca Razor | Romania | + 0.67″ |
| 5 | Emily Diamond | Great Britain | + 1.23″ |
| 6 | Aiyanna Stiverne | Canada | + 1.58″ |
| 7 | Catia Azevedo | Portugal | + 1.82″ |
| 8 |  Christine Botlogetswe | Botswana | + 2.53″ |