Eric Dale, 49, admitted unlawful sexual intercourse,during a trial at Burnley Crown Court.
The defendant, of Brierfield, was cleared of two counts of child abuduction and three of indecent assault on the direction of Judge Raymond Bennett. He had denied all the charges against him.
The jury had heard claims Dale had sex with both the victim and her friend after they ran away from home and stayed at his house in June last year.
Both girls were reported missing by their mothers and were not found until after they had stayed at Dale’s for two nights.
The schoolgirls were given cider to drink and were said to have got on Dale’s bed.
The defendant stayed with the victim while the other went downstairs with another man. Dale got undressed, removed the girl’s underwear and had sex with her.
Sex came to a halt when the other girl came into the room and both girls went downstairs with the other man.
The other girl told police Dale had wanted to be left alone with her friend and she had gone in the defendant’s bedroom to see him on top of her. Dale told her to leave the room.
The prosecution had alleged Dale had tried to kiss the other girl and then got on top of her.
The court was told Dale told police both girls removed their tops and said they were 16.