In this research, a new guideline map has been introduced for the production process of acrylonitrile–butadiene–styrene (ABS) compounds in upstream units. Therefore, one-step mixing (method A) and two-step mixing (method B) in production of ABS composite were conducted and analyzed. On the other hand, introducing inorganic fillers during the final extrusion process in upstream units can result in complex behaviors of the ABS compounds, which are influenced by the positioning of the filler within the matrix. Therefore, the silane-modified wollastonite has been included in the ABS composites via two mixing methods and subsequently assessed. The findings indicate that the tensile modulus and the impact strength of composite containing a low level of wollastonite (5%) prepared by method B surpassed those obtained through method A. However, the observed results were inverted when the wollastonite content increased to 10%. At a low concentration of wollastonite, method A demonstrated a more significant transfer of filler into the butadiene rubber phase than method B. Conversely, at an elevated filler level, method B exhibited an increased extent of filler movement. The evaluated properties revealed that the mixing method significantly influences the improvement of the mechanical properties of the reinforced ABS composites. Nevertheless, additional research is crucial to comprehensively understand of the influence of mixing protocols on the microstructural characteristics of ABS composites.