The name Sunamganj has derived from its founder, Sipahi Sunamuddin, who established a bazaar on the bank of the river Surma. In ancient period, Sunamganj was part of Rarh Kingdom that included western part of Sylhet, Habiganj, Netrokona, Kishorganj and northern part of Mymensingh. After the conquest of Sylhet in 1303 by Muslims under the spiritual guidance of Hazrat Shah Jalal; Hazrat Shah Kamal, one of the companions of Hazrat Shah Jalal, vanquished the entire district of Sunamganj, but it was not directly governed during Hazrat Shah Kamal’s lifetime. It was his second son, Shah Moazzamuddin named Moazzamabad and administered the entire district from Shaharpara.
Sunamganj is renowned for bards and folk music. Mystic poet Hason Raja, Durbin Shah, Syed Shahnoor, Radharaman Dutta, Radhamadhav Dutta, Shah Abdul Karim, Muniruzzaman Munir, Nurul Ghani, Qari Amiruddin and many more.
In 1336 BS a devastating flood occurred as a result of breaking down a damn in Manipur. This flood is popularly known as 'White Water Flood'. A pernicious earthquake on 12 June 1897 caused heavy loss of lives and establishments.
However, the Nankar Rebellion of Sukhair in 1922-23 is notable. Many political leaders and activists of Sunamganj were involved in the anti-British movement. The leftist movement spread over the district after the partition of 1947.
During the war of liberation many encounters were held between the freedom fighters and the Pakistani Army. Sunamganj was liberated on 6 December 1971.