The 17-year-old girl was found dead in a house in Foston Close, Mansfield, at 1.45am today.
Nottinghamshire Police said officers were called to the property because of concerns for the safety of the girl.
A 21-year-old man was arrested on suspicion of murder and remains in custody.
The house is sealed off and under police guard while scenes of crime experts comb the property for clues to help them establish what exactly happened.
A Nottinghamshire Police spokesman said: "An investigation has been launched following the discovery of a 17-year-old girl's body at a house in Foston Close, Mansfield.
"Officers were called at 1.45am in relation to the concern for her safety.
"A 21-year-old man has been arrested on suspicion of murder and is to be questioned by officers.
Detectives are conducting their inquiries with Crime Scene Investigation colleagues at the scene.
"Despite the investigation being in its early stages, this is believed to be an isolated incident and officers are not looking for anyone else in relation to it."
Anyone with information should call South Yorkshire Police on 101.