MnZn power ferrites for MHz and wide temperature applications were prepared by ceramic process and effects of Co2O3 and MoO3 co-doping on the microstructure and magnetic properties have been investigated, and MnZn power ferrite with ultra-high cut-off frequency of 14.2 MHz has been prepared. It has been revealed that the grain size of the MnZn ferrite can be homogenize via the co-doping of Co2O3 and MoO3, giving rise to enhanced electrical resistivity, compensated magnetocrystalline anisotropy and reduced domain wall displacement. Effective reduction of the power loss with improved temperature stability and cut-off frequency have been achieved by synergistic function of Co2O3 and MoO3 via liquid-phase sintering increasing the possibility of Co2+ cation entering into the spinel lattice.