The 95-year-old monarch, who is also Queen of Canada thanked emergency responders and volunteers for their “tireless work” and for providing comfort and support to those in need.
A major storm destroyed roads, houses and bridges in what may be the costliest natural disaster in the country’s history.
Around 14,000 residents were still displaced from their homes on Friday and at least one person has been confirmed dead.
Her message, which was signed Elizabeth R, was sent in both English and French.
It read: “My thoughts are with the people of British Columbia as you continue to confront the recent catastrophic flooding and gradually begin the process of recovery and rebuilding.
“I am grateful for the tireless work of the many first responders and volunteers who continue to provide comfort and support to their fellow Canadians during this difficult time.”