| Date | 9 – 10 October 2018 | 
|---|---|
| Status | YOG | 
| Location | Natatorium, Parque Olímpico de la Juventud, Villa Soldati, Buenos Aires | 
| Participants | 36 from 35 countries | 
| Pos | Swimmer | NOC | R1 | SF | Final | |||
|---|---|---|---|---|---|---|---|---|
| 1 | Sara Junevik |  SWE | 26.91 (2 h5) | 26.75 (1 h1) | 26.40 (1) | Gold | ||
| 2 | Anastasiya Shkurdai |  BLR | 26.56 (1 h4) | 26.65 (=1 h2) | 26.62 (2) | Silver | ||
| =3 | Polina Yegorova |  RUS | 27.43 (4 h5) | 26.98 (5 h1) | 26.68 (=3) | Bronze | ||
| =3 | Angelina Köhler |  GER | 26.96 (3 h5) | 26.65 (=1 h2) | 26.68 (=3) | Bronze | ||
| 5 | Anicka Delgado |  ECU | 27.28 (2 h3) | 26.92 (3 h1) | 26.80 (5) | |||
| 6 | Lin Xintong |  CHN | 26.84 (1 h3) | 26.83 (2 h1) | 27.10 (6) | |||
| 7 | Mayuka Yamamoto |  JPN | 26.84 (1 h5) | 27.12 (3 h2) | 27.17 (7) | |||
| 8 | Tamara Potocká |  SVK | 27.69 (4 h4) | 26.95 (4 h1) | 27.48 (8) | |||
| 9 | Miriam Guevara |  MEX | 27.42 (2 h4) | 27.70 (6 h2) | – | |||
| 10 | Kyla Leibel |  CAN | 27.45 (5 h5) | 27.30 (5 h2) | – | |||
| 11 | Julieta Lema |  ARG | 27.55 (1 h2) | 27.16 (6 h1) | – | |||
| 12 | Beatriz Padrón |  CRC | 27.56 (3 h4) | 28.18 (8 h2) | – | |||
| 13 | Diana Nazarova |  KAZ | 27.64 (2 h2) | 27.71 (7 h1) | – | |||
| 14 | Chen Yu-Rong |  TPE | 27.66 (3 h3) | 27.17 (4 h2) | – | |||
| 15 | Aleyna Özkan |  TUR | 27.76 (5 h4) | 27.77 (7 h2) | – | |||
| =16 | Ieva Maļuka |  LAT | 27.85 (3 h2) | – | – | |||
| =16 | Michaela Ryan |  AUS | 27.85 (4 h3) | 28.06 (8 h1) | – | |||
| =16 | Alexandra Schegoleva |  CYP | 27.85 (6 h4) | – | – | |||
| 19 | Lismar Lyon |  VEN | 27.90 (6 h5) | – | – | |||
| 20 | Kornelia Fiedkiewicz |  POL | 27.98 (7 h5) | – | – | |||
| 21 | Natalie Kan |  HKG | 28.01 (5 h3) | – | – | |||
| 22 | Nea-Amanda Heinola |  FIN | 28.04 (7 h4) | – | – | |||
| 23 | Yuliya Stadnyk |  UKR | 28.15 (1 h1) | – | – | |||
| 24 | Valentina Becerra |  COL | 28.21 (8 h4) | – | – | |||
| 25 | Karolina Jurczyk |  POL | 28.25 (6 h3) | – | – | |||
| 26 | Kristýna Štemberová |  CZE | 28.33 (7 h3) | – | – | |||
| 27 | Victoria Russell |  BAH | 28.40 (4 h2) | – | – | |||
| 28 | Elinah Phillip |  IVB | 28.65 (8 h5) | – | – | |||
| 29 | Duné Coetzee |  RSA | 28.70 (2 h1) | – | – | |||
| 30 | Mariel Mencía |  DOM | 28.80 (5 h2) | – | – | |||
| 31 | Maddy Moore |  BER | 28.96 (6 h2) | – | – | |||
| 32 | Inés Marín |  CHI | 28.99 (7 h2) | – | – | |||
| 33 | Theresa Hefel |  LIE | 29.52 (3 h1) | – | – | |||
| 34 | Ruvarashe Gondo |  BOT | 32.16 (4 h1) | – | – | |||
| 35 | Margie Winter |  FSM | 32.40 (5 h1) | – | – | |||
| 36 | Anastasiya Tyurina |  TJK | 33.37 (6 h1) | – | – | |||
| Leoni Richter |  SUI | – (DNS h2) | – | – | ||||
| Julia Mrozinski |  GER | – (DNS h3) | – | – | 
Top 16 advance to the semi-finals.
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Yuliya Stadnyk |  UKR | 28.15 | |||
| 2 | – | Duné Coetzee |  RSA | 28.70 | |||
| 3 | – | Theresa Hefel |  LIE | 29.52 | |||
| 4 | – | Ruvarashe Gondo |  BOT | 32.16 | |||
| 5 | – | Margie Winter |  FSM | 32.40 | |||
| 6 | – | Anastasiya Tyurina |  TJK | 33.37 | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Julieta Lema |  ARG | 27.55 | |||
| 2 | – | Diana Nazarova |  KAZ | 27.64 | |||
| 3 | – | Ieva Maļuka |  LAT | 27.85 | |||
| 4 | – | Victoria Russell |  BAH | 28.40 | |||
| 5 | – | Mariel Mencía |  DOM | 28.80 | |||
| 6 | – | Maddy Moore |  BER | 28.96 | |||
| 7 | – | Inés Marín |  CHI | 28.99 | |||
| – | Leoni Richter |  SUI | – | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Lin Xintong |  CHN | 26.84 | |||
| 2 | – | Anicka Delgado |  ECU | 27.28 | |||
| 3 | – | Chen Yu-Rong |  TPE | 27.66 | |||
| 4 | – | Michaela Ryan |  AUS | 27.85 | |||
| 5 | – | Natalie Kan |  HKG | 28.01 | |||
| 6 | – | Karolina Jurczyk |  POL | 28.25 | |||
| 7 | – | Kristýna Štemberová |  CZE | 28.33 | |||
| – | Julia Mrozinski |  GER | – | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Anastasiya Shkurdai |  BLR | 26.56 | |||
| 2 | – | Miriam Guevara |  MEX | 27.42 | |||
| 3 | – | Beatriz Padrón |  CRC | 27.56 | |||
| 4 | – | Tamara Potocká |  SVK | 27.69 | |||
| 5 | – | Aleyna Özkan |  TUR | 27.76 | |||
| 6 | – | Alexandra Schegoleva |  CYP | 27.85 | |||
| 7 | – | Nea-Amanda Heinola |  FIN | 28.04 | |||
| 8 | – | Valentina Becerra |  COL | 28.21 | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Mayuka Yamamoto |  JPN | 26.84 | |||
| 2 | – | Sara Junevik |  SWE | 26.91 | |||
| 3 | – | Angelina Köhler |  GER | 26.96 | |||
| 4 | – | Polina Yegorova |  RUS | 27.43 | |||
| 5 | – | Kyla Leibel |  CAN | 27.45 | |||
| 6 | – | Lismar Lyon |  VEN | 27.90 | |||
| 7 | – | Kornelia Fiedkiewicz |  POL | 27.98 | |||
| 8 | – | Elinah Phillip |  IVB | 28.65 | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Michaela Ryan |  AUS | 27.88 | |||
| 2 | – | Ieva Maļuka |  LAT | 27.93 | |||
| 3 | – | Alexandra Schegoleva |  CYP | 27.94 | 
Top 8 advance to the final round.
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Sara Junevik |  SWE | 26.75 | |||
| 2 | – | Lin Xintong |  CHN | 26.83 | |||
| 3 | – | Anicka Delgado |  ECU | 26.92 | |||
| 4 | – | Tamara Potocká |  SVK | 26.95 | |||
| 5 | – | Polina Yegorova |  RUS | 26.98 | |||
| 6 | – | Julieta Lema |  ARG | 27.16 | |||
| 7 | – | Diana Nazarova |  KAZ | 27.71 | |||
| 8 | – | Michaela Ryan |  AUS | 28.06 | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| =1 | – | Angelina Köhler |  GER | 26.65 | |||
| =1 | – | Anastasiya Shkurdai |  BLR | 26.65 | |||
| 3 | – | Mayuka Yamamoto |  JPN | 27.12 | |||
| 4 | – | Chen Yu-Rong |  TPE | 27.17 | |||
| 5 | – | Kyla Leibel |  CAN | 27.30 | |||
| 6 | – | Miriam Guevara |  MEX | 27.70 | |||
| 7 | – | Aleyna Özkan |  TUR | 27.77 | |||
| 8 | – | Beatriz Padrón |  CRC | 28.18 | 
| Pos | Lane | Swimmer | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | – | Sara Junevik |  SWE | 26.40 | |||
| 2 | – | Anastasiya Shkurdai |  BLR | 26.62 | |||
| =3 | – | Polina Yegorova |  RUS | 26.68 | |||
| =3 | – | Angelina Köhler |  GER | 26.68 | |||
| 5 | – | Anicka Delgado |  ECU | 26.80 | |||
| 6 | – | Lin Xintong |  CHN | 27.10 | |||
| 7 | – | Mayuka Yamamoto |  JPN | 27.17 | |||
| 8 | – | Tamara Potocká |  SVK | 27.48 |