Eric Stanton from Avonmore Park in Mayfield was with some friends in a field near the site of the former John Barleycorn Hotel in Riverstown when the accident happened.
Irishtimes.com says it is believed that Eric was riding bareback on one of half a dozen horses grazing in the field when the horse stumbled near the Glashaboy, throwing the boy into the fast flowing river.
Two friends who were with Eric raised the alarm following the incident which happened shortly after 6pm on Saturday evening and the emergency services responded quickly.
Gardaí from Glanmire along with members of Cork City Fire Brigade and paramedics attended at the scene which is opposite the John O’Callaghan Park amenity area in Riverstown.
A major search operation was launched and the boy was recovered some 30 minutes later by members of the Fire Brigade, having been swept downstream. He was under water for some time.
Eric was in a critical condition and paramedics worked on him at the scene to try and resuscitate him before he was transferred by ambulance to Cork University Hospital.
Doctors at the emergency department continued to treat Eric but he failed to regain consciousness and he was pronounced dead shortly after 11pm on Saturday night.
Supt Tom Myers of Mayfield Garda Station described the incident as “a terrible tragedy” and extended his sympathies to the boy’s family on their loss.