The 17-year-old was walking through Sixmilewater Park on Saturday evening with a friend when she was struck by the vehicle.
She suffered multiple injuries to her face and legs and had to be taken to hospital.
The man driving the silver-coloured moped did not stop at the scene. Police said he was described as being of slim build, average height and less than 20 years old.
Anyone who witnessed the incident, which happened at around 10.15pm, or who has any more information is asked to call the PSNI in Newtownabbey on 0845 600 8000.