Swimming at the 2025 World Aquatics Championships – Women's 100 metre backstroke

The event is expected to center on the rivalry between Regan Smith of the United States and Kaylee McKeown of Australia, who have dominated the event since 2020. The two have alternated ownership of the world record, with Smith currently holding it at 57.13 from the 2024 U.S. Olympic Trials, while McKeown won Olympic gold in Paris with 57.33. Both have produced sub-58 times this season, Smith leading with 57.46 and McKeown at 57.65. Other contenders include Katharine Berkoff of the United States, a 2024 Olympic bronze medalist with a 57.83 best, and Canada’s Kylie Masse, a consistent international medalist with a 57.70 lifetime best. Several rising athletes, including Carmen Weiler of Spain and Taylor Ruck of Canada, may also challenge for podium positions. ==Qualification==

Each National Federation was permitted to enter a maximum of two qualified athletes in each individual event, but they could do so only if both of them had attained the "A" standard qualification time. For this event, the "A" standard qualification time was 1:00.46. Federations could enter one athlete into the event if they met the "B" standard qualification time. For this event, the "B" standard qualification time was 1:02.58. Athletes could also enter the event if they had met an "A" or "B" standard in a different event and their Federation had not entered anyone else. Additional considerations applied to Federations who had few swimmers enter through the standard qualification times. Federations in this category could at least enter two men and two women to the competition, all of whom could enter into up to two events. ==Records==

Prior to the competition, the existing world and championship records were as follows. The following record was established during the competition: ==Heats==

The heats took place on 28 July at 10:02. ==Semifinals==

The semifinals took place on 28 July at 19:53. Swim-off The swim-off was started on 28 July at 20:39. ==Final==

The final took place on 29 July at 19:50. ==References==