Prince Isariyabhorn or Phra Chao Boromwongse Ther Phra Ong Chao Isariyabhorn (RTGS: Isariyaphorn) (Thai: พระเจ้าบรมวงศ์เธอ พระองค์เจ้าอิศริยาภรณ์) (21 October 1888 – 21 September 1892), was a Prince of Siam (later Thailand. He was a member of the Siamese Royal Family. He was a son of Chulalongkorn, King Rama V of Siam. His mother was , daughter of . He had a younger brother, Prince Anusara Siriprasadh. Prince Isariyabhorn died at the age of 3 years and 11 months on 21 September 1892.