The 15-year-old girl, Emilie Fortuzi, was reported missing from the institution in the city of Fribourg at around 5.25pm, cantonal police said.
The girl cannot express herself but she can understand French, police said.
According to the description provided by police she is 165 centimetres tall with short, chestnut-brown hair and was wearing glasses.
She was last seen wearing a black ski pants with a purple and grey winter jacket and brown and beige running shoes.
Police are asking anyone who may have seen the girl or who has information about her whereabouts to contact the nearest police station or to phone 026 305 17 17.