Suppressing the through-plane component of the thermal conductivity caused by synthetic graphite (SG) alignment was decreased by loading of recycled carbon fiber (CF) into SG loaded polypropylene (PP) composites. The effect of CF loading into SG loaded PP composites on thermal stability, viscoelastic, and morphological properties were also investigated by thermogravimetric analysis, dynamic mechanical analysis, and scanning electron microscopy, respectively. CF loading into SG loaded PP composites increased through-plane conductivity considerably rather than in-plane conductivity. 20 wt% CF additions into 50 wt% SG increased through-plane and in-plane thermal conductivity values by 12.5 and 1.3 times, respectively. Storage and loss moduli of composites significantly increased with the increasing fiber weight content, particularly 20 wt%. Besides, while SG decreases the mechanical properties of PP, CF loading into SG loaded PP composites increased the mechanical properties.