This study established a robust two-dimensional (2D) numerical model for plastic waste (PW) pyrolysis driven by self-sustaining smoldering. The smoldering-driven pyrolysis reactor consists of a smoldering chamber filled with char and sand and a pyrolysis chamber with a porous-matrix bed and PW particles. The PW could be melted and decomposed into value-added volatiles driven by the stable char smoldering heat. The findings revealed that the pyrolysis duration and product distribution could be regulated by the char concentration and Darcy air velocity. Higher PW contents shortened the volatiles’ residence time in the pyrolysis chamber and controlled the pyrolysis product yields. The increased PW content could enhance the PW processing capacity potentially resulting in the recovery of more liquid and gaseous fuels. Moreover, the reactor’s geometry significantly affected the pyrolysis chamber’s temperature distribution and the PW processing capacity.