We report a detailed theoretical and experimental study of the effect of Cr substitution in place of Fe on the structural, magnetic, transport, and electronic properties of Co₂FeSi alloys. A comprehensive structural analysis is performed using anomalous XRD and EXAFS spectroscopy. Quaternary Heusler compounds Co₂Fe_1−xCr_xSi with Cr content (x = 0.1, 0.3, 0.5) are found to crystallize in cubic structure.The synchrotron-based EXAFS studies reveal that the antisite disorder increases with an increase in Cr concentration. The saturation magnetization values in all alloys are found to be less than those expected from the Slater-Pauling rule, which may be due to some inherent disorder. Theoretical calculations successfully verify the experimental findings and reveal Si at Fe/Cr antisite disorder to be energetically the most favorable. A detailed resistivity analysis in the temperature range of 5–300 K is performed, taking into account different scattering mechanisms. The residual resistivity ratio is found to decrease with increasing Cr concentration. A disorder-induced resistivity minimum due to a weak localization effect is seen for x = 0.5. The resistivity measurements also indirectly support the half-metallic nature in these alloys. A detailed analysis shows that the half-metallic character survives up to 100 K for x = 0.1, whereas the alloys with x = 0.3 and 0.5 show the signature of the half-metallic nature even at higher temperatures.First-principles calculation carried out with a more robust exchange correlation functional (namely HSE-06) confirms the half metallicity in the entire concentration range. Unlike the generalized gradient approximation and the local-density approximation , this clearly confirms a full band gap in the minority spin channel and hence confirms the robust half-metallic character of Co₂FeSi- and Cr-substituted alloys. Theoretically simulated band gap and magnetic moments compliment the experimental findings and are compared wherever possible. All these properties make Co₂Fe_1−xCr_xSi a promising material for spintronics application.