The 14-year-old girl was discovered in Bourtreehill Park, Irvine, North Ayrshire, at around 11.45am on Monday.
A post-mortem examination is due to take place to establish the cause of death.
A police spokeswoman said: “Police Scotland is currently investigating the circumstances surrounding the death of a 14-year-old girl found dead within Bourtreehill Park at around 11.45am on Monday September 11.
“The death is being treated as unexplained.
“It is anticipated that a post-mortem examination will take place in due course to establish the exact cause of death and a report will be sent to the procurator fiscal.”