Recent investigations have demonstrated that potassium titanate whiskers (PTW) as reinforcement can significantly improve the mechanical properties of aluminum alloys. Building on these findings, 7xxx alloy-5.0 vol% PTW composites were fabricated via rheological processing, with characterization conducted on microstructural evolution during solidification. With prolonged processing duration, PTW exhibits progressively improved dispersibility in the alloy matrix. Specifically, a 59.3% reduction in the average whisker length was observed following 30 s of semi-solid slurrying, attributed to the shear-induced fragmentation during the treatment. Meanwhile, the composite’s tensile strength reached 363.0 ± 3.7 MPa, gaining ca. 29.0% increase. Findings from this study demonstrate that high-performance Al-PTW composites can be fabricated via semi-solid rheological processing, concurrently enabling a reduction in PTW reinforcement content. Additionally, this research deepens the comprehension of PTW breakage and distribution mechanisms during the solidification of semi-solid aluminum melts.