This chapter presents a comprehensive overview of the advanced monitoring and sensing technologies transforming well integrity surveillance and management. As the limitations of conventional methods—such as periodic pressure readings and discrete logging—become increasingly evident in the face of complex well designs and dynamic operational conditions, the industry is transitioning toward continuous, real-time monitoring systems that deliver greater sensitivity, spatial coverage, and diagnostic capability. At the forefront of this transformation is fiber-optic sensing, with Distributed Temperature Sensing (DTS), Distributed Acoustic Sensing (DAS), and Distributed Strain Sensing (DSS) technologies turning the entire wellbore into a continuous sensor array. These systems provide high-resolution data streams for early leak detection; thermal and mechanical stress monitoring; and real-time evaluation of cement curing, flow dynamics, and structural deformation. Complementary technologies like wireless downhole sensors are also emerging, offering untethered data acquisition in annuli and deep subsurface zones previously unreachable without compromising barrier integrity. The chapter also explores advancements in conventional logging tools, including high-resolution ultrasonics, multi-frequency electromagnetic logs, and through-tubing diagnostics. These innovations improve the accuracy of cement evaluation, corrosion mapping, and leak detection, ensuring the continued relevance of traditional logging in modern well integrity programs. Finally, the chapter highlights the growing role of drones and robotics for surface and structural inspections. These platforms enhance safety, reduce inspection costs, and expand coverage for wellheads, risers, and platform structures—critical components of overall well integrity. Through illustrative figures and real-world case studies, the chapter emphasizes the importance of integrating multiple data sources—fiber optics, wireless telemetry, periodic logs, and robotic inspection—into a unified well integrity monitoring strategy. This integrated approach enables earlier anomaly detection, supports predictive maintenance, reduces costly interventions, and enhances decision-making throughout the well’s lifecycle. As the industry navigates more challenging environments and energy transition applications, advanced sensing technologies offer a robust foundation for ensuring safe, reliable, and sustainable well operations.