The girls' 800 metre freestyle event in swimming at the 2014 Summer Youth Olympics took place on 19 August at the Nanjing Olympic Sports Centre in Nanjing, China.

[1] This event was a timed-final where each swimmer swam just once.

The top 8 seeded swimmers swam in the evening, and the remaining swimmers swam in the morning sessions.

The first round was held on August 19, at 11:02, and the final was held on August 19, at 18:00.

[1]