Due to the low thermal conductivity of PCM, the enhancement of thermal performance becomes a crucial issue for the application of PCM-based heat sinks in electronic device cooling. To address this, efficient and integrative PCM-based heat sinks using fin and structure porous material (SPM) are designed and fabricated by additive manufacturing (AM). This work aims to investigate thermal performance of PCM-based heat sinks and the role of fin and SPM used as thermal conductivity enhancers (TCEs). The enhanced heat transfer mechanisms in PCM-based heat sinks using different types of TCEs are determined, and parametric analysis is conducted considering various volume fractions of TCEs (10%, 15%, and 20%). Moreover, the effects of heating power levels and convective heat transfer coefficients on thermal behavior of PCM-based heat sink are analyzed. The results indicate that incorporating SPM in heat sink enhances thermal performance more effectively than using fins for an equivalent TCE fraction. Both heating power and convective heat transfer coefficient have a significant on thermal performance. This research demonstrates the potential of the novel heat sink with SPM in cooling electronic devices and provides the experimental and numerical database for the optimal design and future application of PCM-based heat sink.