Noah Lomax, aged 15, was reported missing after being last seen at 9:30am yesterday morning in the Crookes area of Sheffield.
Officers found the body of the 15-year-old this morning in the Conisborough area of Doncaster.
A South Yorkshire police spokesman said: "Police searching for missing 15 year old boy Noah Lomax have sadly today discovered a body in Conisbrough, Doncaster.
"Formal ID has confirmed it's Noah. His family are receiving support and ask their privacy be respected at this sad time."