Despite major advances in addressing the dispersion of carbon nanotubes (CNTs) in polymers and their interfacial interactions, exploring a facile approach for massively creating them is still fascinating. We interestingly find that the CNT dispersion is considerably improved in polypropylene (PP), and similar to 19.1 wt % of PP chains were in situ chemically grafted onto CNT surfaces only using a trace of AlCl3 via a one-step melt-blending. Compared with the PP/CNT composite, adding 0.2 wt % of AlCl3 enables an increase in tensile strength and Young's modulus of 30% and 25%, respectively. Moreover, the elongation at break is almost maintained, while adding CNTs alone causes significant decreases. Additionally, 0.2 wt % AlCl3 makes the thermal degradation temperature further improved. These remarkable improvements in properties are mainly attributed to better dispersion of CNTs and enhanced interfacial compatibility. This work opens up an innovative approach for scalable preparation of polyolefin/CNT composites applying to industrial production.