Mandurah Police are urgently seeking information to help them locate Karli.
She was last seen in the Coodanup area headed towards the Mandurah CBD.
The 15-year-old is described as having a slim build with red-brown hair which is tied back with an undercut.
Karli was last seen wearing a grey hoodie with the slogan “Good for Nothing”, with pink and grey check pyjama bottoms and black school shoes.
If you have seen Karli, or know of her whereabouts, please contact the Police Assistance Centre on 131 444 and quote Ref: 527699