Eight-year-old Rhys Miller from Lewisham was last seen at around 5pm on Wednesday in Idonia Street, Deptford, south east London, the Met had said.
Given his age Scotland Yard said they were “extremely concerned for his welfare” and they appealed for help in tracing him.
However, overnight Rhys was said to have been found “safe and well”.
No more details have been formally announced.
Hundreds of people had shared appeals for information after police deemed the disappearance “high risk”.
Police inquiries will continue.