Abstract 2D half‐metallic materials that have sparked intense interest in advanced spintronic applications are essential to the developing next‐generation nanospintronic devices. This study has adopted a first‐principles calculation method to predict the magnetic properties of intrinsic, Se‐doped, and biaxial strain tuning Cr 2 AsP monolayer. The Janus Cr 2 AsP monolayer is proven to be an intrinsic ferromagnetic (FM) semiconductor with an exchange splitting bandgap of 0.15 eV at the PBE+U level. Concentration‐dependent Se doping, such as Cr 2 AsSe x P (x = 0.25, 0.50, 0.75), can regulate Cr 2 AsP from FM semiconductor to FM half‐metallicity. Specifically, the spin‐up channel crosses the Fermi level, while the spin‐down channel has a bandgap. More interestingly, the wide half‐metallic bandgaps and spin bandgaps make them have important implications for the preparation of spintronic devices. At last, it also explore the effect of biaxial strain from ‐14% to 10% on the magnetism of the Cr 2 AsP monolayer. There appears a transition from FM to antiferromagnetic (AFM) at a compressive strain of ‐10.7%, originating from the competition between the indirect FM superexchange interaction and the direct AFM interaction between the nearest neighboring Cr atoms. Additionally, when the compressive strain is ‐2% or the tensile strain is 6%, the semiconducting Cr 2 AsP becomes a half‐metallic material. These charming properties render the Janus Cr 2 AsP monolayer with great potential for applications in spintronic devices.