The first heats of the Women's 100 m Butterfly took place on the morning of Sunday, 26 July.

The semi-final took place in the evening session of 26 July and the final took place on the evening of 27 July at the Foro Italico in Rome, Italy.

In the final, 7 of the 8 swimmers finished within the same second, and 5 within the same 0.1 of a second.

Prior to this competition, the existing world and competition records were as follows: The following records were established during the competition: Key: CR = Championship record, NR = National record Note: The Dutch Record in this event is Inge de Bruijn's former World Record (56.61), which may help to explain why Veldhuis was the only finalist not to set a National Record (NR).