Ambulance crews were called to Thorpes Road, near to the park in Heanor, on the afternoon of Saturday 18 June 2022 to reports that Mikey Harrison had suffered serious injuries – he died later that day.
His father, Michael Harrison, was charged with his murder in July 2022, and had previously admitted a charge of manslaughter but denied his murder.
Appearing at Derby Crown Court, the 41-year-old of Eaton Terrace, Nottingham, admitted to murdering Mikey.
He will be sentenced at a later date.