Structural sustainability and resilience have become critical issues for existing civil engineering infrastructure (i.e. bridges and buildings), which are susceptible to damage over time due to the ageing of materials, climate change, and natural hazards (i.e. floods and earthquakes). Therefore, using advanced composite materials provides an efficient solution for structural retrofitting. Due to their high strength-to-weight ratio, superior durability in adverse environments, and fast implementation, Fibre Reinforced Polymer (FRP) composites are widely used in strengthening existing structures as externally bonded reinforcement (EBR) systems. Mortar-based composites (Fabric-Reinforced Cementitious Matrix (FRCM) composites) have emerged as alternative solutions to FRPs, offering more environmentally friendly and fire-resistant options. However, long-term environmental conditions (e.g. temperature changes, moisture cycles) and fatigue (cyclic loading) could potentially promote debonding in structures strengthened with EBR systems, leading to brittle failure modes. Therefore, bond health monitoring and early damage detection in structures are essential to prevent catastrophic failures and enhance safety. This study presents an overview of debonding detection in concrete structures strengthened with composite materials. It focuses on several non-destructive testing (NDT) methods, including radar-based techniques, to identify debonding damage in externally strengthened concrete structures. The benefits and challenges of these methods are discussed to propose effective solutions for monitoring structures after retrofitting with EBRs. Additionally, preliminary experimental results are presented and discussed, focusing on layered timber specimens and the effectiveness of Radio Frequency Identification (RFID) technology. RFID technology, which could sense debonding at the interfaces, demonstrated an efficient inspection with beneficial characteristics and promise for detecting debonding in strengthened concrete structures.