W–Cu composite powders prepared via the wet chemical method in the form of W-coated Cu contributed greatly to the materials' density and the homogeneity. The powders were modified to prepare large quantities of W–Cu composites with excellent properties via metal injection molding (MIM). In this study, the precursors’ reaction process, the formation mechanism of W-coated Cu, and MIM process were systematically investigated. Results showed that W–Cu composite powders in this coating form could ensure the homogeneity of W and Cu and reduce Cu loss during sintering. In addition, W–Cu composites that fulfill the performance specifications for electronic packaging have been effectively synthesized through MIM employing the novel polyoxymethylene (POM)-based binders. Regarding thermal properties, the W–15Cu composites exhibit an impressive thermal conductivity of 212 W/(m·K) and a minimal coefficient of thermal expansion at 7.01 ppm/°C. These characteristics outperform those of other materials documented in related literature. This study provided a useful referential value to the combination of W–Cu composites in scientific research and engineering applications.