Fiber Bragg gratings (FBG) are extensively used in optical add-drop multiplexers/demultiplexers, optical cross-connect switches, optical sensors and many others in optical fiber telecommunication networks. In this study, FBG was employed as an optical sensor for pile monitoring on steel and concrete structures particularly in bridges and buildings. The measurement was conducted in accordance to PWD (Public Works Department) requirements and the test showed compatible results to the vibrating wire strain gauge (VWSG) used in pile monitoring by PWD. The FBG sensors mounted onto the mild steel rod as a device-under-test have provided high sensitivity, good accuracy and linearity.