The girls' 100 metre freestyle event at the 2018 Summer Youth Olympics took place on 8 and 9 October at the Natatorium in Buenos Aires, Argentina.

[1] The heats were started on 8 October at 10:12.

[2] The semifinals were started on 8 October at 18:40.

[3] The final was held on 9 October at 19:25.

[4]