Annabelle, 15, has not been seen since 9pm last Saturday, November 4, and is considered “vulnerable” due to her age.
She has gone missing before but previously returned home within 24 hours.
Scarborough Police’s Sgt Tom Rollinson said: “Annabelle, the police, your family and friends are extremely worried about you. If you see or hear this appeal we urge you to contact the police, your family or friends and let us know that you are safe.”
Annabelle is thought to have left Scarborough on a train and could be in the company of a boy her own age.
She has links to the Leicester, Northampton, West Midlands, Merseyside and Norfolk areas.
Annabelle is described as white and slim, with very dark long straight hair that is usually worn scrunched up.
When she was last seen she was wearing two jumpers, pink Minnie Mouse pyjama bottoms with grey jogging bottoms over the top, a black Superdry jacket and white Adidas trainers.
Anyone with information is asked to ring the police on 101.