Amy Perry, 17, was last seen on New Street in Dodworth on June 15 but officers believe she may have left the area, possibly travelling to Essex.
She is described as having thick, long blonde hair and was last seen wearing a black skirt, black leather jacket and suede high heels. She is also carrying a green and blue handbag.
She has not made contact with her family since Saturday and they are growing increasingly concerned for her welfare.
Anyone who has seen Amy, or knows where she is is asked to contact officers on 101 quoting incident number 1024 of June 15.