The disclosed invention relates to a fire sprinkler shut-off tool for stopping water flow from an activated fire sprinkler head. Due to the lack of any automatic safety release mechanisms, such tools currently on market suffer the disadvantage of requiring constant monitoring in case fire rekindles. The shut-off tool comprising a pair of adjustable clamping arms and an actuator assembly for adjusting and fixing the clamping arms addresses the safety issue by integrating a fusible link locking tab into the actuator assembly. The presence of a nearby fire melts and separates the locking tab thereby releasing the clamping arms from an activated fire sprinkler head. The shut-off tool also addresses the safety problem of firemen or building maintenance personnel using a shut-off device that requires two hands while working from a ladder as this device can be easily used with one hand. The shut-off tool also achieves the object of universal fit on most fire sprinkler heads by use of the adjustable angled clamping arms and by locating a sealing surface on each of the clamping arms so as to permit operation with fire sprinklers mounted in an upright position.