Mylie Bovell was last seen at around 2pm on Friday, July 11 in Green Street Green Road, Dartford.
She is described as white, about 5ft tall, with light brown hair usually tied back in a ponytail, and blue eyes.
She is believed to be wearing a grey top, black shorts, white socks, and black Crocs.
Mylie is known to explore the Dartford area and may use public transport to travel into London.
Anyone with critical information about her whereabouts is urged to call 999, quoting reference 11-0997.
For non-urgent information, the public can contact police via live chat on the Kent Police website or by calling 101.
