ABSTRACT Unmanned aerial vehicles (UAVs) have become indispensable assets across military, commercial, and civil domains due to their operational flexibility, cost‐efficiency, and real‐time sensing capabilities. However, the increasing integration of UAVs into critical infrastructure, combined with their reliance on wireless communications, Global Positioning System, and embedded control systems, has significantly expanded their cybersecurity attack surface. Despite growing research efforts, a comprehensive understanding of the unique security challenges facing UAV systems remains fragmented. This survey systematically analyzes the multifaceted cybersecurity threats targeting UAV platforms, encompassing communication links, navigation subsystems, onboard controllers, and ground control stations. We develop a unified threat taxonomy that classifies attacks such as spoofing, jamming, denial‐of‐service, hijacking, and malware injection, and assess their impacts on the core security pillars of confidentiality, integrity, and availability. Furthermore, existing defense mechanisms—including cryptographic protocols, intrusion detection systems, machine learning‐based anomaly detection, secure routing algorithms, and authentication schemes—are critically evaluated with respect to their effectiveness, scalability, resource consumption, and suitability for UAV‐specific operational constraints. Unlike previous surveys, this study synthesizes cross‐layer defense strategies and highlights open research gaps that remain underexplored. Finally, emerging directions such as blockchain integration, federated learning, and quantum‐resistant cryptographic frameworks are discussed, aiming to inspire robust and adaptive security architectures for next‐generation UAV ecosystems. This survey offers valuable insights for researchers, system architects, and policymakers committed to advancing UAV cybersecurity in increasingly contested and dynamic environments.