Pyrolysis is a promising solution for the valorization of plastic and road asphalt waste within a circular economy framework. This study investigates the co-pyrolysis of polypropylene (PP) with road asphalt and its individual components (bitumen and mineral fraction) in order to better understand chemical interactions and optimize liquid product yields. Experiments were conducted in a semi-batch reflux reactor under an inert nitrogen atmosphere. The heating rate was set at 10 ◦C/min from room temperature to 500◦C in the pyrolysis zone, with varying mass ratios of PP and asphalt. The pyrolysis products were analyzed using GC-MS, μ-GC and ¹H NMR. The results show that the addition of asphalt significantly increases the liquid product yield, while the chemical distribution of the products remains almost unchanged. A clear synergistic interaction between PP and asphalt was observed in all blends, resulting in higher pyrolytic oil yields compared with pure PP pyrolysis. This synergy reached its maximum at a PP/asphalt ratio of 2:1 with an increase of the oil yield of 6.3 ± 0.7 wt%. This effect is attributed to the stabilizing role of bitumen, which mitigates secondary reactions promoted by mineral catalysis present in the asphalt. Furthermore, the analysis of the produced oils indicates that their chemical composition remains similar to that of oils derived from pure PP, while their viscosity is only slightly affected by the presence of bitumen. This indicates that the presence of asphalt does not compromise the quality of the pyrolytic oil. These findings highlight the potential of PP/asphalt co-pyrolysis as an innovative approach for the simultaneous conversion of these two waste streams into valuable hydrocarbons, opening new perspectives for the chemical recycling of plastic and bituminous materials.