It is believed Lucy may be in the Barnsley area after leaving her home last night, September 24 at around 11:10pm.
She is 5 ft 3ins tall, of a slim build with long brown and purple hair.
The 16-year-old is believed to be wearing red trainers, a grey Adidas jacket with blue stripes and black jeans.
Anyone with information should call 101 quoting incident number 88 of 25 September 2020.