Halloysite nanotubes (HNTs) and intumescent flame retardant (IFR)-filled 80/20 (wt/wt) polypropylene/acrylonitrile–butadiene–styrene (PP/ABS) blend and their composites in the presence of dual compatibilizer have been prepared using twin screw extruder followed by injection molding. There exists the formation of α- and β-form of PP crystals in addition to enhancement in crystallinity of PP phase by an addition of HNTs and IFR in 80/20 (wt/wt) PP/ABS blend and their composites in the presence of dual compatibilizer. In addition, scanning electron microscopy (SEM) reveals the formation of matrix-droplet morphology, and the dispersion of HNTs and IFR in 80/20 (wt/wt) PP/ABS blend and its composites in the presence of dual compatibilizer results in a refinement in matrix-droplet morphology. This has resulted in an enhancement in tensile and impact properties of HNTs- and IFR-filled 80/20 (wt/wt) PP/ABS blend and their composites in the presence of dual compatibilizer. Thermal stability also increases by an addition of HNTs and IFR in 80/20 (wt/wt) PP/ABS blend and their composites in the presence of dual compatibilizer due to formation of intumescent char. © The Author(s) 2017.