Cooling rate significantly influences the microstructural evolution and mechanical properties of TiAl sheets following multipass hot-pack rolling. In this study, Ti-43Al-4Nb-1Mo- 0.2 B (at.% , TNM) sheets were prepared through furnace-cooling and air-cooling methods after rolling. The microstructural morphology, phase transformation, and recrystallization behavior of TNM sheets were systematically investigated at different cooling rates. Furthermore, the mechanical properties of the alloy at room temperature were evaluated, and the underlying deformation mechanisms were clarified. The results indicate that slow cooling facilitates the α2 →βo phase transition both within and at the boundaries of α2 /γ lamellar colonies while also promoting the nucleation and growth of equiaxed γ recrystallized grains surrounding these colonies. However, compared with slow cooling, rapid cooling promotes the α2 →γ phase transition, resulting in a decrease in the α2 /γ interlamellar spacing from 140 nm to 60 nm. In addition, the strength and plasticity of the TNM sheets are simultaneously enhanced because the γ laths have heterogeneous thicknesses and few γ recrystallized grains surround the α2 /γ lamellar colonies under rapid cooling conditions, achieving a tensile strength of 1 140 MPa and an engineering strain exceeding 1%.