| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | ms* | 
|---|---|---|---|---|---|---|---|
| 1 | 1 | 3 | 457 | Solomon Lekuta |  KEN | 1:48.19 Q | |
| 2 | 2 | 3 | 204 | Marino BLOUDEK |  CRO | 1:48.54 Q | |
| 3 | 3 | 3 | 307 | Markhim Lonsdale |  GBR | 1:48.60 Q SB | .597 | 
| 4 | 4 | 3 | 262 | Adisu GIRMA |  ETH | 1:48.60 q | .600 | 
| 5 | 1 | 1 | 646 | Josh HOEY |  USA | 1:48.86 Q | |
| 6 | 2 | 1 | 153 | Eliott CRESTAN |  BEL | 1:48.92 Q | |
| 7 | 1 | 4 | 454 | Alex Ngeno KIPNGETICH |  KEN | 1:49.03 Q | .026 | 
| 8 | 3 | 1 | 205 | Sven Cepuš |  CRO | 1:49.03 Q SB | .030 | 
| 9 | 4 | 1 | 203 | Juan Diego Castro |  CRC | 1:49.18 q NU20R | |
| 10 | 5 | 3 | 155 | Pieter SISK |  BEL | 1:49.40 q | .392 | 
| 11 | 6 | 3 | 102 | Oussama Cherrad |  ALG | 1:49.40 q PB | .395 | 
| 12 | 2 | 4 | 534 | Marcelo Pereira |  POR | 1:49.49 Q PB | |
| 13 | 3 | 4 | 656 | Rey Rivera |  USA | 1:49.53 Q | |
| 14 | 4 | 4 | 246 | Eduardo Romero |  ESP | 1:49.56 | |
| 15 | 5 | 1 | 377 | Beant Singh |  IND | 1:49.66 | |
| 16 | 1 | 2 | 393 | Simone BARONTINI |  ITA | 1:49.73 Q | |
| 17 | 6 | 1 | 484 | Mohamed Abouettahery |  MAR | 1:50.15 | |
| 18 | 7 | 3 | 119 | Lachlan Raper |  AUS | 1:50.23 | |
| 19 | 2 | 2 | 293 | Alex Botterill |  GBR | 1:50.26 Q | |
| 20 | 5 | 4 | 399 | Andrea Romani |  ITA | 1:50.28 | |
| 21 | 6 | 4 | 515 | Marco Vilca |  PER | 1:50.47 | |
| 22 | 3 | 2 | 607 | Mehmet ÇELİK |  TUR | 1:50.61 Q | |
| 23 | 4 | 2 | 415 | Kimar Farquharson |  JAM | 1:50.76 | |
| 24 | 7 | 1 | 132 | Archie Wallis |  AUS | 1:51.25 | |
| 25 | 5 | 2 | 183 | Ruach Chuol Padhal |  CAN | 1:51.61 | |
| 26 | 6 | 2 | 361 | Lőrinc Varga |  HUN | 1:51.67 | |
| 27 | 8 | 1 | 331 | Oskar SCHWARZER |  GER | 1:52.39 | |
| 28 | 7 | 4 | 489 | Charaf Zahir |  MAR | 1:52.95 | |
| 2 | 260 | Teddese LEMI |  ETH | DQ | 
ms - Milliseconds - shown when two or more competitors finish with the same time down to hundredths of a second