The RE (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) and Mn ions co-doped Co–Zn ferrites were prepared by solid-state reaction method. X-ray diffraction, infrared spectra, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and infrared emission measurement (IRE-2) were employed to investigate the effect of the substitution RE 3+ and Mn ions for Fe 3+ ones on the spinel structure, the chemical homogeneity, and the infrared emission properties of the Co–Zn ferrites. The substitution leads to non-monotonous change of the lattice parameters and infrared emissivity properties, which is mainly attributed to the partial cation exchange among the spinel structure of Co–Zn ferrites. The infrared emission properties of Co–Zn ferrites seem to be greatly influenced by the co-doped of RE 3+ and Mn ions—maxima values were 0.96–0.97, found for LaF, NdF and GdF, respectively.