Abstract <p>The effects of superimposed shear flow (SSF) during solidification are investigated on microstructure, elemental distribution, and performance in 2055 Al–Li alloy, with experimental characterization and numerical simulation. Relative to traditional gravity casting (i.e., non-SSF), SSF refines eutectic Al₂Cu phases at grain boundaries (GBs), with reduction in area fraction from 25.04 to 18.51%. The compositional fluctuation of Cu at GBs is lightened under SSF, suggesting alleviation in micro-segregation. The macro-segregation of solutes caused by melting point and density difference is alleviated under SSF which produces circumferential, radial, and upper-down exchanges of melt, as verified by numerical simulation. Moreover, acicular <i>T</i>₁-Al₂CuLi phase absent under non-SSF is observed in the grain interior of SSF ingot, arising from alleviating micro-segregation and hence supersaturation within grains of Cu, Li solutes under SSF. The number density of <i>T</i>₁ declines from edge, to R/2, and to center of SSF ingot, attributed to the difference in shear flow intensity evidenced by melt flow simulation. SSF ingot in casting state exhibits superior mechanical properties and under the same homogenization treatment achieves more adequate dissolving of eutectic Al₂Cu, alongside complete dissolution of acicular <i>T</i>₁. The findings underscore SSF as a maneuverable and effective route to produce high-quality Al–Li alloy castings.</p> Graphical abstract <p></p>