Holly Hickman, aged 14, was last seen in the McDonalds on Waters Meeting Road, Astley at around 6.30pm on Sunday 28 June 2015.
Holly is described as white, around 5ft 3in tall, with long brown hair and brown eyes.
She was last seen wearing a black and grey jacket, an orange top, denim shorts, black tights and white trainers.
Detective Inspector Charlotte Cadden based at Astley Bridge police station said: “If you have seen Holly since Sunday evening, or if you know of her whereabouts now, please get in touch.
“Or if Holly herself can see this appeal, then please call officers at Bolton so we can ensure you are safe.”
Anyone with information is asked to call police at Astley Bridge station on 0161 856 5758.