| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | 
|---|---|---|---|---|---|---|
| 1 | 1 | 3 | 2502 | Stephenie Ann MCPHERSON |  JAM | 49.34 Q PB | 
| 2 | 1 | 1 | 1684 | Marileidy PAULINO |  DOM | 49.38 Q NR | 
| 3 | 2 | 1 | 2501 | Candice MCLEOD |  JAM | 49.51 Q PB | 
| 4 | 1 | 2 | 1131 | Shaunae MILLER-UIBO |  BAH | 49.60 Q | 
| 5 | 3 | 1 | 1583 | Roxana GÓMEZ |  CUB | 49.71 q PB | 
| 6 | 4 | 1 | 3853 | Quanera HAYES |  USA | 49.81 q | 
| 7 | 2 | 3 | 3847 | Allyson FELIX |  USA | 49.89 Q SB | 
| 8 | 2 | 2 | 2033 | Jodie WILLIAMS |  GBR | 49.97 Q PB | 
| 9 | 3 | 3 | 1151 | Sada WILLIAMS |  BAR | 50.11 NR | 
| 10 | 3 | 2 | 2500 | Roneisha MCGREGOR |  JAM | 50.34 | 
| 11 | 4 | 2 | 3857 | Wadeline JONATHAS |  USA | 50.51 | 
| 12 | 4 | 3 | 3164 | Natalia KACZMAREK |  POL | 50.79 | 
| 13 | 5 | 1 | 1606 | Eleni ARTYMATA |  CYP | 50.80 NR | 
| 14 | 5 | 2 | 2924 | Paola MORÁN |  MEX | 51.06 SB | 
| 15 | 5 | 3 | 1388 | Kyra CONSTANTINE |  CAN | 51.22 | 
| 16 | 6 | 3 | 1920 | Amandine BROSSIER |  FRA | 51.30 | 
| 17 | 7 | 3 | 3223 | Cátia AZEVEDO |  POR | 51.32 | 
| 18 | 6 | 2 | 2995 | Lieke KLAVER |  NED | 51.37 | 
| 19 | 7 | 2 | 2249 | Aliyah ABRAMS |  GUY | 51.46 | 
| 20 | 6 | 1 | 1112 | Susanne GOGL-WALLI |  AUT | 51.52 PB | 
| 21 | 8 | 2 | 1762 | Aauri Lorena BOKESA |  ESP | 51.57 PB | 
| 22 | 7 | 1 | 2021 | Ama PIPI |  GBR | 51.59 | 
| 23 | 8 | 1 | 1629 | Lada VONDROVÁ |  CZE | 51.62 | 
| 24 | 8 | 3 | 2991 | Lisanne DE WITTE |  NED | 52.09 |