Two-dimensional half-metallic ferromagnet materials have attracted significant attention because of their fascinating physical properties. Herein, a two-dimensional Mn₂AsSb monolayer ferromagnetic material was designed, and its intrinsic half-metallicity and magnetic properties were systematically investigated through density functional theory (DFT) and the nonequilibrium Green’s function (NEGF) method. Research results show that Mn₂AsSb monolayer has a spin gap of 2.44 eV, exhibits intrinsic half-metallicity, and can achieve 100% spin-polarization within a wide Fermi window (>1.5 eV). Meanwhile, the Mn₂AsSb monolayer has a high Fermi velocity (1.13×10⁵ m/s), a large magnetic crystalline anisotropy (0.025–0.35 meV/(unit cell)), a high electrical conductivity (~10¹¹ S/cm²), and a low Gilbert damping (2.49×10^–5). Furthermore, the effective exchange interaction of Mn₂AsSb monolayer is explored by using the spin-polarized Green’s function formalism. The calculations give a reasonable spin wave stiffness (92.73 meV·Å²) and a high Curie temperature ( 263.7\;\textK< T_\mathrmc \lt 462.4\;\textK ). Therefore, the Mn₂AsSb monolayer material has intrinsic half-metallicity and excellent magnetic properties, which demonstrates its promising application prospect in the next generation spintronic devices.