Queen Camilla unveiled a portrait of Second World War resistance agent Noor Inayat Khan at the RAF Club in London on Tuesday.
“I feel very humble to unveil such a brave woman," Queen Camilla was quoted by PA as saying.
Ms Khan served as a British secret agent in Nazi-occupied France during the war, where she was sent undercover as a children's nurse in June 1943 to aid the French resistance.
She sent important messages back to the UK from behind enemy lines, but was eventually caught by the Nazis.
Ms Khan refused to co-operate or decode messages despite being tortured by the Gestapo. She was then sent to Dachau concentration camp, where she was executed on September 12, 1944. She was 30 years old.
Her heroism was recognised by both Britain and France, who posthumously awarded her the George Cross and the Croix de Guerre, respectively.
She has since been nicknamed the "spy princess", in reference to her royal lineage. She was a direct descendant of Tipu Sultan, the 18th-century Muslim ruler of Mysore, in India.
Her life is documented in the 2006 biography Spy Princess: The Life of Noor Inayat Khan, and she is commemorated by a blue plaque at 4 Taviton Street in Bloomsbury, London, where she lived during 1942-43.
Honoured by Queen Camilla
Queen Camilla unveiled a portrait of Ms Khan painted by artist Paul Brason at the RAF Club.
She also announced the room would be renamed the Noor Inayat Khan Room.
“I am delighted to name this room after her," PA quoted Queen Camilla say saying.
“It’s a wonderful painting."
Mr Brason based the portrait from a handful of photographs of Ms Khan, whose undercover work meant she was not often photographed.
“One of the difficulties about painting a portrait of someone who was operating undercover, particularly in the Second World War, is that people who work undercover don’t like photographs being taken of them," he told PA.
“So that means, in regards to the reference material, there is not very much of it.
“Certainly none of it in what, dare one calls it, her professional capacity, because she would avoid it.”
Ms Khan's 95-year-old cousin, Mahmoud Khan, was present at the event and described the portrait as "truly splendid".
“It is an excellent likeness,” he said. “That is what struck me most, that the painter did so much to bring her personality to life."
The unveiling was part of Queen Camilla's first day of solo engagements after the summer, with King Charles III remaining in Scotland.
Earlier in the day, she attended a poetry recital and tea party at Fielding Primary School in Ealing, London.