This manuscript reports on a homogenized model for the anisotropic thermal conductivity of support structures constructed by the laser powder bed fusion (L-PBF) process, and its application to the numerical simulation of the L-PBF process. Considering both analytical and numerical approaches, the model is developed across a temperature interval encompassing the entire L-PBF process. Subsequently, the homogenized material properties are incorporated into a thermal finite element model (FEM) of the L-PBF process to consider the effects of the support structures, taking into account their anisotropic properties. The simulation results of the L-PBF process indicate that the support structures act as a thermal barrier, retaining more heat in part compared to direct printing on the substrate. The implementation of homogeneous thermal conductivity in the L-PBF process simulation demonstrates its efficiency and potential application to better control heat transfer during part construction.