Density functional theory based on full-potential linearized augmented plane-wave method is used to investigate the structural, electronic, and magnetic properties of Co2Cr1-xMnxAl (x = 0, 0.25, 0.5, 0.75, 1) alloys. The parent full Heusler alloy (Co2CrAl) exhibits the least total magnetic moment of 3 μB/f.u. For the alloyed structures, this value is found to increase as a function of Mn concentration. The magnitudes of Co2Cr1-xMnxAl total magnetic moment show a trend consistent with the Slater–Pauling behavior. Co2CrAl full Heusler alloy reveals a half-metallic behavior with an indirect band gap along the Γ-X symmetry line. For the non-stoichiometric structures, the energy levels of the valence band shift to higher energies until they cross the Fermi level for x = 0.75 and 1.