The rapid expansion of urban development has led to the extensive construction of civil infrastructures. However, these urban development zones frequently face potential geohazards, primarily due to the lack of detailed site investigations and long-term monitoring of subsurface geological conditions. Understanding the temporal and spatial distributions of underground multi-field information is vital for successful engineering construction and effective utilization of urban underground space. In this study, a fiber optic nerve system (FONS) was utilized in the Tianfu New Area, Sichuan Province, China, to obtain comprehensive subsurface multi-physical information, including geological deformation, temperature, and surface hydrological data. The FONS incorporates three advanced fiber optic sensing techniques, i.e. fiber Bragg grating (FBG), Brillouin optical time domain reflectometry (BOTDR), and Raman optical time domain reflectometry (ROTDR). Fully- and quasi-distributed strain/temperature sensing cables have been installed in nine monitoring boreholes, covering various geological features such as plains, terraces, and areas within active fault zones. The field monitoring results confirm the feasibility of employing FONS for geological investigations within urban development zones, offering a valuable reference for future applications of this cost-effective technology in geohazard mitigation.