Police confirmed the 12-year-old boy passed away two days after the incident.
He had got into difficulties in the River Tay at Stanley on Sunday afternoon.
The Coastguard was called at around 13:40 and he was rushed to Ninewells Hospital in Dundee.
Police confirmed today that the boy died in the early hours of Tuesday morning.
A spokesperson said: "Our thoughts are with his family and friends at this very tragic time."
Inquiries into the incident are continuing.