The rising global demand for energy, together with continued dependence on fossil fuels, has intensified the need for sustainable technologies for energy production and waste valorization. Thermochemical conversion of waste into fuels has emerged as a promising approach; however, the separate pyrolysis of biomass or plastics generally produces oils with poor stability, low quality, and undesirable chemical composition. In this context, co-pyrolysis has attracted considerable attention as an effective strategy to exploit the complementary characteristics of hydrogen-rich plastics and oxygen-rich biomass, thereby enhancing hydrocarbon formation and improving fuel quality. Nevertheless, although the effects of temperature and catalysts have been widely investigated, the role of pressure in improving oil quality remains insufficiently understood. In this study, the pressurized catalytic co-pyrolysis of traditional Chinese medicine residue as a biomass and polystyrene was investigated under nitrogen using FeCo/ZSM-5 as a bifunctional catalyst. Isoconversional kinetic analysis over the conversion range of α = 0.2–0.9 demonstrated the catalytic role of FeCo/ZSM-5 in enhancing the feasibility of the reaction. The average apparent activation energies of the non-catalytic blend were 178.3 and 190.27 kJ mol-1 by KAS and FWO, respectively, and decreased to 155.45 and 163.23 kJ mol-1 after catalyst addition. High correlation coefficients (R2 > 0.94) confirmed the reliability of the kinetic evaluation. Temperature, pressure, catalyst composition, and feedstock ratio strongly influenced product distribution and oil quality. The optimum conditions were identified at 600 °C and 1.5 MPa, where the maximum liquid yield of 63.5 wt.% and an oil lower heating value of 41.37 MJ kg-1 were achieved. TCMR: PS ratio of 1:3 gave the most favorable co-pyrolysis performance, while FeCo/ZSM-5 promoted hydrogen transfer, deoxygenation, and aromatization, resulting in a maximum BTEX yield of 46.3%.