Advancements in the electronics industry have led to miniaturized components with increased computing power, which resulted in serious heat management issue. Under such technological trend, the development of new multifunctional packaging materials with excellent thermal conductivity and electrical resistivity, which can be used for heat dissipation, is becoming increasingly important. A recent research revealed the possibility of using foaminginduced filler alignment to promote the effective thermal conductivity (k_eff). In this context, this thesis research aims to develop thermally conductive polymer matrix composite (PMC) foams that can provide a solution to the heat management of new electronic devices. First, an analytical model was constructed to confirm the feasibility of foaming-induced k_eff enhancement. This model considered filler alignment caused by foaming-induced stress field, and calculated the k_eff using the concept of thermal resistor network. Second, a comprehensive experimental study was conducted to parametrically reveal the dependency of PMC’s k_eff on foam morphological parameters, including filler size, foam expansion ratio, cell size, and cell population density. Low density polyethylene (LDPE)-hexagonal boron nitride (hBN) composites blown by Expancel® microspheres were studied as a case example to prove the concept. This study successfully fabricated thermally conductive PMC foams with k_eff higher than their solid counterparts, which is the first time reported in the literature. In particular, the k_eff of PMC foams filled with 9.21 vol% of hBNAC6041 (i.e., submicron-scale) or hBNPT110 (i.e., micron-scale) reached as high as 1.16 W·m⁻¹·K⁻¹ and 0.97 W·m⁻¹·K⁻¹, respectively. These values represented 26% and 21% increases over those of their solid counterparts. Finally, physical foaming was investigated as a processing method to fabricate PMC foams by using carbon dioxide as the physical blowing agent. The study of physical foaming aims to investigate the possibility of producing thermally conductive PMC foams in a more cost-effective way. Due to the small cell size, no foamed sample demonstrated k_eff higher than solid counterpart. However, the k_eff was not significantly compromised, while the mass density and material cost were reduced.