This study presents a numerical analysis of thermoelectric generators (TEGs) integrated with a heat sink and phase change materials (PCMs), focusing on their combined impact on thermal management and power output. The module, comprising a bismuth telluride (Bi2Te3)-based TEG coupled with a paraffin wax PCM, was evaluated using finite element analysis across a range of PCM thicknesses. Results indicate that incorporating PCM effectively reduces the cold-side temperature during the melting process, thereby sustaining a more stable temperature gradient (ΔT) across the module. This leads to significant enhancement in the output power by maintaining a higher ΔT between the hot and cold junctions during the phase change process. As a result, the peak output power increased by approximately 3.5 times compared to a standalone TEG operating under identical conditions. While peak power magnitude varied only slightly with PCM thickness, the duration of peak output improved significantly from 60 s at 1 mm to 360 s at 3 mm. Among the configurations studied, a PCM thickness of 3 mm delivered the most effective balance between thermal buffering and power stability. These findings offer quantitative insights for the design of compact PCM-assisted TEG modules intended for operation under fluctuating thermal inputs.