The insufficient absolute strength of Mg-Li alloys severely restricts their aerospace applications. To address this limitation, a dual-phase Mg-Li alloy with enhanced strength was fabricated through rapid solidification combined with hot-press sintering and extrusion. The optimized alloy exhibited yield and ultimate tensile strengths of 283 MPa and 306 MPa under quasi-static loading, respectively, while retaining a uniform elongation of 6%. Multiscale microstructural characterization via XRD, SEM-EBSD, and TEM revealed that rapid solidification induced remarkable grain refinement and precipitate redistribution. Subsequent thermomechanical processing achieved full dynamic recrystallization with refined grains. Crucially, the rapid solidification kinetics notably altered Al partitioning, favoring solid solution in magnesium phase over precipitation in lithium phase. These microstructural modifications activate synergistic strengthening mechanisms: 1) Hall-Petch hardening from grain refinement, 2) dispersion strengthening via nano-precipitates, 3) dislocation strengthening from substructures, and 4) solid solution effects from Al supersaturation. This work establishes a microstructure design paradigm for high-performance Mg-Li alloys through coupled rapid solidification and thermomechanical processing.