Ellie Brannen and Reah Hall, both aged 14, disappeared from their home addresses on Tuesday night (March 15).
Police said they were last seen together in Layton at around 9.20am on Wednesday morning (March 16).
Chief Insp Cara Leadbetter, of Lancashire Police, said: “We believe they may be together and are asking anybody with information about where they might be to get in touch with us straight away.
“We would also ask Ellie and Reah themselves, if they see this appeal, to make contact with us.”
Ellie is described as white, of slim build, with long, dark brown hair.
She was last seen wearing a black jacket with fur around the hood, a grey tracksuit and Nike shoes.
Reah is described as white, around 4ft 6in tall, of slim build, with blue eyes and shoulder-length light brown hair.
She was last seen wearing a red River Island coat with a fur hood, black or grey leggings and black Nike trainers.
Both have links to Blackpool and Preston.
Anybody with information should call 101, quoting log LC-20220314-0126.