Hannah Davies went missing from Bradford Leisure Exchange in Vicar Lane at about 8.50pm on Wednesday, March 23.
Detective Constable Ian Walker, of Bradford District CID, said: “We are very concerned for Hannah’s welfare and urgently need to establish her whereabouts.
“She is known to frequent both Bradford and Leeds and we have been carrying out extensive enquiries to trace her since she went missing.
“We would ask that anyone who has seen her or who has any information that could assist in finding her contact us immediately.”
She is described as white, about 5ft 7ins tall and slim. She has blue eyes and mousy brown, shoulder-length hair.
She was wearing a black leather jacket, blue denim leggings, black and white trainers and was carrying a purple handbag.
Anyone with information is asked to contact the special operations room at Trafalgar House Police Station via 101 quoting log number 1502 of March 23.