The Harry Potter author was granted the prestigious title by Prince William at Buckingham Palace on Tuesday, saying she was "deeply honored and proud" to receive the honor, which is limited to 65 people "of distinction" at any one time.
"To be included in the distinguished and diversely talented company of the other Companions of Honor, especially as a female writer, is a particular privilege," added Rowling, who was honored for her services to literature and philanthropy.
The decoration comes nearly 20.5 years after the U.K. release of the first novel in her best-selling fantasy series, Harry Potter and the Philosopher's Stone. In 2001, she also received the Order of the British Empire (OBE) from His Royal Highness, the Prince of Wales, for services to children's literature.
Rowling -- chic in a head-to-toe blue ensemble with a freshly painted red manicure -- seemed to be in good spirits while accepting the medal