The youngster, Nathaniel, was last seen at around 10.30am at a property on Bluebell Close, in the Firth Park area of Sheffield.
He is mixed race, slim build and has black hair.
It is believed that Nathaniel was wearing black tracksuit bottoms, a grey coat and black trainers when he was last seen.
South Yorkshire Police said: “Officers are becoming increasingly concerned for Nathaniel's welfare and want to speak to anybody who has seen him.
“Have you seen him? Do you know where he might be?”
A photograph has been shared in the hope that Nathaniel will be recognised and sightings will be reported to the police.
Anyone with information on his whereabouts or which may help police officers should call South Yorkshire Police on 101 and quote incident number 367 of April 15.