A novel fiber optical monitoring concept for real-time localization of activated fire sprinkler heads is presented and discussed in this work. The concept is implemented by a designed fiber optical sensor and standard telecom components, such as optical time-domain reflectometer (OTDR), single-mode glass fiber, couplers, and reflectors. The proposed sensor based on optic reflection and interrupting mechanism allows to monitor the current status of sprinkler head and to differentiate the sprinkler activation from unwanted interferences, for example, glass fiber breakage. According to the experiments and calculations, hundreds of sprinkler heads can be monitored by a single OTDR device that results in net system energy consumption well below 100 mW per sensor point. The proposed monitoring concept opens up new perspectives for applying fiber optical sensors in fire protection methods. It can be used as a self-contained sensor network or in combination with modern fire detection and alarm systems in a primary-secondary-configuration.