The RE3+, MnO2:CoZn (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) ferrite ceramics were prepared by solid-state reaction method. The change in the magnetic and infrared emission properties of the samples due to the co-doping of RE3+ and Mn4+ ions have been studied. X-ray diffraction studies show that the main phase of the system is the spinel phase and the secondary phase (REFeO3) is formed on co-doping of RE3+ and Mn4+ ions. The distribution of cation in the tetrahedral and octahedral sites was analyzed using X-ray photoelectron spectroscopy and Mössbauer spectroscopy. It was observed that larger RE3+ ions easily occupy the interstitial sites or grain boundary, but not the octahedral sites of the spinel. Magnetic and infrared emission measurements indicate that saturation magnetization decreases and infrared emissivity and coercivity exhibit the nonlinear variations with kinds of RE3+ ions. The magnetic and infrared emission properties of samples seem to be greatly influenced by the cation distribution caused by synergistic effect of RE3+ and Mn4+ ions, in which the rare earth elements of La, Nd, and Gd play a more important role to improve the infrared emissivity and coercivity than others.