<p>The integration of sensors into metallic structures has gained significant attention, leading to the emergence of “Smart Metallic Structures (SMS).” These structures feature embedded sensors designed for real-time data acquisition of functional signals (e.g., strain, temperature, pressure, humidity) for structural monitoring. Notably, the advent of metal additive manufacturing (AM) technologies has enabled the direct embedding of functional sensors into metallic components, making a transformative step toward fully integrated smart structures. This capability is particularly valuable for critical applications where continuous monitoring is vital to ensure safety, efficiency, durability, and improved performance. Despite rapid progress, there remains a need for a comprehensive review that systematically summarizes sensor-embedding strategies, material–process interactions, performance evaluation methods, and key challenges. This review addresses that gap by synthesizing recent developments in additively manufactured SMS and elucidating how AM technologies are being leveraged to integrate sensing functionalities. The objectives of this work are to: (i) consolidate recent advancements; (ii) provide a nuanced perspective on the current landscape of sensor-embedded SMS; and (iii) identify key research challenges to guide future work and facilitate broader adoption. Unlike prior reviews that primarily focus on either AM techniques or standalone sensor technologies, this work presents a holistic framework linking materials, manufacturing processes, and sensing performance. By mapping current progress and outlining emerging opportunities, this review aims to guide both researchers and industry practitioners toward the development of next-generation intelligent metallic systems.</p>