Somdet Phra Bawornrajchao Maha Sura Singhanat (Thai: ????????????????????????????????; RTGS: Somdet Phra Boworaratchao Mahasurasinghanat) (1744–1803) was the younger brother of Phutthayotfa Chulalok, the first monarch of the Chakri dynasty of Siam.
As an Ayutthayan general, he fought alongside his brother in various campaigns against Burmese invaders and the local warlords.
When his brother crowned himself as the king of Siam at Bangkok in 1781, he was appointed the Front Palace or Maha Uparaj, the title of the heir.
During the reign of his brother, he was known for his important role in the campaigns against Bodawpaya of Burma.