The 93-year-old was snapped sporting a pink ensemble, matching headscarf and carrying her signature handbag.
The photographs come hours after Buckingham Palace confirmed her husband Philip had been hospitalised.
A statement read: "The Duke of Edinburgh travelled from Norfolk this morning to the King Edward VII Hospital in London for observation and treatment in relation to a pre-existing condition.
"The admission is a precautionary measure, on the advice of His Royal Highness' Doctor."
A source revealed to PEOPLE that the Duke did not travel by ambulance.
“It was a planned admission, and he walked into the hospital unaided,” the source claims.
It’s unclear how long Philip will remain in the hospital — or if he’ll miss Christmas with the family.
The Duke of Edinburgh retired from a life of royal duties in 2017 when he was 96 years of age.