Princess Ajrabarni Rajkanya or Phra Chao Boromwongse Ther Phra Ong Chao Ajrabarni Rajkanya (RTGS: Atcharaphanni Ratchakanya) () (7 July 1872 – 15 November 1910), was the Princess of Siam (later Thailand). She was a member of Siamese royal family. She was a daughter of Chulalongkorn, King Rama V of Siam.
Her mother was Chao Chom Manda Talab Ketutat, daughter of Phraya Viangnai Narubal. She had a younger brother, Prince Raphi Phatthanasak, the Prince of Ratchaburi, who is known as Father of the Thai Law.
Princess Ajrabarni Rajkanya died on 15 November 1910, a month after her father's death, at the age of 38.