DESŪ SIṄGH, BHĀĪ (d. 1781), was the second of the five sons of Bhāī Gurbakhsh Siṅgh of the well-known Bhāī family, deriving its name from the celebrated Bhāī Bhagatū, contemporary of three successiv Gurūs, Gurū Arjan, Gurū Hargobind and Gurū Har Rāi. According to Bhāī Santokh Siṅgh, Garb Gañjanī Ṭīkā, Desū Siṅgh was the fifth in the line of Bhāī Bhagatū's descendants. His father, Bhāī Gurbakhsh Siṅgh was a close associate of Ālā Siṅgh of Paṭiālā and had carved for himself some territories around Sirhind and Kaithal besides his ancestral possessions in several villages around Bhuchcho, near Baṭhiṇḍā. After his death in 1764, his territories were divided among his sons. Desū Siṅgh collected a force, and, advancing from Bhuchcho, marched straight to Kaithal and defeating Bhīkh Bakhsh and Niāmat Khān, two brothers in possession of Kaithal, established himself there as an independent chief sometime between 1764 and 1768. He began further to extend his territories and seized the town of Thānesar with one of its two forts. This excited the jealousy of another Sikh chief, Mit Siṅgh, who seized the second fort at Thānesar, and after his death, his son, Bhaṅgā Siṅgh, evicted Desū Siṅgh's forces from that town.

         Bhāī Desū Siṅgh also fell out with Rājā Amar Siṅgh, of Patiālā, in 1778, because he did not support the Rājā in his punitive action against Harī Siṅgh, of Siālbā, who had been friendly with the Kaithal chief. After dealing with the Siālbā chief, Rājā Amar Siṅgh sent a force against Kaithal, too, but an attack was averted by the intercession of some of the Bhāī brothers.

         Bhāī Desū Siṅgh died at Kaithal in 1781.