The Duchess of Cornwall has been made a Dame Grand Cross by the Queen as she and Prince Charles celebrate their seventh wedding anniversary.
The honour is the highest female rank in the Royal Victorian Order.
A spokeswoman said the Duchess, 64, would be invested with the insignia of her rank at a later date.
Appointments to the Royal Victorian Order are made by the Queen independently of the government.
The Order was founded in 1896 by Queen Victoria as a way of rewarding personal service.
Camilla has become patron of a number of organisations and has travelled extensively with Charles on official trips.
"It's likely that Camilla's award is in recognition of her many royal engagements at home and abroad over the past seven years and is an indication of her importance within the royal family," says BBC correspondant Fiona Trott.