Semifinal 2
mardi 1 octobre 2019, 19h50 GMT – 19h50 GMT
| Nom | Équipe | Temps | |
|---|---|---|---|
| 1 |  Shaunae Miller-Uibo | Bahamas | 49.66″ |
| 2 |  Wadeline Jonathas | United States | + 0.41″ |
| 3 |  Shericka Jackson | Jamaica | + 0.44″ |
| 4 |  Sada Williams | Barbados | + 1.65″ |
| 5 |  Lisanne de Witte | Netherlands | + 1.75″ |
| 6 | Roxana Gómez | Cuba | + 1.9″ |
| 7 |  Bendere Oboya | Australia | + 1.92″ |
| 8 |  Lada Vondrova | Czech Republic | + 2.59″ |