Achieving a synergistic enhancement of strength and ductility in magnesium alloys remains a persistent challenge due to the intrinsic limitations of their hexagonal close-packed (HCP) crystal structure. In this work, it was found that the strength of ZGW511 alloy was improved to 381 MPa and the elongation was increased to 12% by increasing the rolling speed to 2.5 m/min at 220 °C. It is worth noting that when the rolling speed is 10 m/min, the elongation of the alloy increases to 21% while maintaining the strength of 333 MPa. During high-speed rolling, the temperature field and stress field of the alloy increased simultaneously. Based on the thermal-mechanical coupling effect, the recrystallization rate increased, and the grains were refined. As a result, the alloy retained a high work hardening rate while exhibiting significantly enhanced softening behavior during room-temperature tensile testing. Therefore, the strength and elongation of the alloy increased simultaneously. This work proposed a new strategy to achieve the synergistic improvement of strength and elongation in low rare-earth microalloyed magnesium alloys by optimizing a single rolling parameter.