Jamie O'Sullivan was found "safe and well" at an address in the Ridgeway area of Sheffield on Tuesday afternoon.
He was reported missing from the Haigh Moor Lane area of Swallownest in Sheffield last Wednesday.
South Yorkshire Police revealed that after receiving information suggesting individuals are deliberately hindering officers' efforts to find the schoolboy, a 45-year-old woman from Sheffield has been arrested on suspicion of an offence under the Children Act.
A 16-year-old boy has also been arrested on suspicion of the same offence.
Both remain in police custody.