RCMP in Sooke say the severely injured 58-year-old Otter Point resident woman was found on Friday night.
Staff Sgt. Steve Wright says friends began searching when the woman did not arrive at her home, about six kilometres west of Sooke.
He says the victim, who was wearing a helmet, was located by 9 p.m., but firefighters and paramedics could not revive her.
Police believe she lost control of her ATV and it overturned on top of her.
The woman's name has not been released and Wright says the cause of the accident remains under investigation.