Twin roll casting is a short-process, high-energy-efficiency method for producing aluminum alloy sheets. During the forming process of cast-rolled aluminum alloy sheets, defects such as segregation, coarse secondary phases, and poor properties may occur owing to the quenching effect of the rolling mill rolls. Microalloying can effectively mitigate these defects and enhance the mechanical properties of aluminum alloy sheets produced by cast rolling. In the aluminum alloy twin roll casting process, regulating the recrystallization behavior and improving the microstructure by promoting or suppressing the particle-stimulated nucleation (PSN) effect is critical for producing high-quality cast-rolled sheets. This study prepared six Al-Mg-Si cast-rolled aluminum alloy sheets with varying Zr contents to investigate the evolution of their microstructure and properties, aiming to reveal the influence of Zr content on the recrystallization behavior and mechanical properties of Al-Mg-Si cast-rolled aluminum alloy sheets from the perspective of PSN. The results demonstrated that as the Zr content increased, the grain size initially increased, subsequently decreased, and then increased again. The Zr element was observed to combine with Al to form nano-sized Al₃Zr precipitates with L1₂ structure. These precipitates effectively inhibited the recrystallization behavior associated with PSN in cast-rolled sheets and promoted grain fibrosis. Specifically, when the Zr content was 0.4% (mass fraction), the degree of grain fibrosis reached its maximum; however, with a Zr content of 0.6%, the inhibitory effect of Zr on grain recrystallization was reduced. At this concentration, the coarse D0₂₃-structured Al₃Zr primary phase emerged, exacerbating the PSN effect and increasing the degree of recrystallization in the cast-rolled sheet. Furthermore, as the Zr content increased in the cast-rolled sheet, the size and volume fraction of the Fe-rich phase exhibited a trend of first increasing, then decreasing, and subsequently increasing again. Notably, when the Zr content was 0.3%, the comprehensive mechanical properties of the cast-rolled sheet were optimal. The tensile fracture surface exhibited ductile fracture characteristics, and the Fe-rich phase distribution in the sheet was dispersed. The tensile strength, yield strength, and elongation were measured to be 226.91 MPa, 104.81 MPa, and 15.05%, respectively.