The porous Fe-7.5Cu alloy has attracted significant attention due to its self-lubricating properties, but its insufficient mechanical strength limits its application in high-load environments. This study employs high-vacuum pressureless microwave sintering technology and introduces 0–1.5 wt% nickel-coated graphene nanoplatelets (GNP(Ni)) as a reinforcing phase, significantly enhancing the alloy’s microstructure and mechanical properties. Key findings show that at 1.5 wt% GNP(Ni), the hardness increased by 75.1%, engineering stress improved by 66.1%, and compressive strength rose by 50.0%, with a relatively low ductility loss (14.3%). These enhancements stem from multiple synergistic mechanisms, including grain refinement (Fe grain size reduced from 33.7 nm to 31.6 nm), Orowan strengthening by Fe 3C precipitates, load transfer by GNP(Ni), and interfacial reinforcement effects. However, a high content of GNP(Ni) may induce agglomeration, leading to increased porosity and affecting the uniformity of the alloy’s microstructure. This work reveals the strengthening potential of GNP(Ni) in porous metal matrix composites and offers a scalable strategy for developing lightweight and high-strength materials for aerospace, tribology, and energy applications.