Mission RCMP say the boy was playing outside around 11 a.m. PT, when he followed the family dog onto a pond in the backyard.
Both the boy and his dog fell through the ice, plunging into the freezing water.
Police say the boy's mother rescued him and he was subsequently treated by Mission Fire and Rescue workers.
The boy briefly lost consciousness and was airlifted to B.C. Children's Hospital, where he remains.
A hospital spokesperson said the parents had not given them consent to discuss the boy's condition with the media, but that the situation remained "fluid."
The family dog did not survive the incident.