Chloe Woolsey, 15, was last seen leaving her home at 8.20pm on Sunday August 7 and getting into a taxi.
The taxi took her to the Harvester near to Brighton Pier but she has not been seen since.
PC Lucie Collier said: “We are concerned about Chloe she is only 15 and has been out all night. We believe she is still in Brighton though she lives in Rustington and also has friends in Bognor.
“She is 5’ 7” with shoulder length dark brown hair. She wears a nose ring and was last seen wearing black skinny jeans, black crop top and boots and was carrying a brown handbag.”
Anyone who has seen her or knows where she is is asked to contact police on [email protected] quoting serial 1635 of 07/08.