Abstract: The rapid development of global industrialization and urbanization, coupled with the dramatic impact of climate change, has significantly increased the risk of geological disasters. Effective monitoring and early warning systems are essential for mitigating the impact of these hazards. This paper explores the application and development of fiber optic sensing technology in geological safety monitoring. Through a systematic literature review, the principles of fiber optic sensing technology and its progress in the application within three areas—landslide disasters, tunnel disasters, and seismic monitoring—are examined. The review indicates that fiber optic sensing technology can monitor strain, temperature, vibration, fluid, and gas characteristics in real time, providing crucial support for the early warning and mitigation of geological hazards. Additionally, this technology can capture coupled information of various physical parameters simultaneously, enhancing the understanding of the destabilization mechanisms in geological bodies under complex environments and the assessment of protective structure safety. Despite its excellent performance in geological hazard monitoring, fiber optic sensing technology faces challenges in optimizing fiber optic layout, data processing, and real-time early warning systems. Future developments should focus on improving the durability and effectiveness of fiber optic monitoring systems and integrating artificial intelligence to enhance the accuracy of geological hazard identification and prediction models, as well as the intelligence level of monitoring systems.