<p>Magnesium (Mg) matrix composites have emerged as one of the most promising lightweight engineering materials for aerospace, automotive, biomedical, and electronic applications due to their low density, high specific strength, excellent machinability, and superior damping characteristics. The increasing demand for lightweight structural materials with enhanced mechanical and thermal performance has accelerated research on magnesium-based composites reinforced with ceramic particles, carbon nanomaterials, and hybrid reinforcements. However, pure magnesium suffers from poor wear resistance, low creep resistance, and high susceptibility to corrosion, which restrict its widespread application in structural systems. To overcome these limitations, various reinforcements such as silicon carbide (SiC), aluminum oxide (Al₂O₃), titanium carbide (TiC), boron carbide (B₄C), graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs) have been incorporated into magnesium matrices. This review paper provides a comprehensive overview of magnesium matrix composites (MMCs), focusing on reinforcement materials, fabrication techniques, microstructural characterization, thermal behaviour, mechanical properties, tribological performance, corrosion resistance, and industrial applications. Various synthesis routes including stir casting, powder metallurgy, friction stir processing, squeeze casting, spark plasma sintering, and additive manufacturing are critically discussed. The role of characterization techniques such as SEM, EDS, XRD, Raman spectroscopy, DSC, and TGA in evaluating the structure-property relationships of Mg composites is also presented. Furthermore, recent developments, major challenges, and future research directions in the field of magnesium composites are highlighted. This review aims to provide researchers and engineers with a detailed understanding of the current state and future potential of Mg-based composite materials.</p>