High permittivity and low-loss SrTiO3/Ni0.8Zn0.2Fe2O4 (STO/NZO) composites with concrete-like morphology were prepared through hybrid processing route. The dielectric properties in the low-frequency range (100 Hz-1 MHz) follow the rule of Maxwell-Wagner interfacial polarization. The dielectric and magnetic properties in the high-frequency range (10 MHz-1 GHz) exhibit a well integration of dielectric and magnetic properties in the composites with low dielectric and magnetic losses. The STO/NZO composites show good dielectric properties and magnetic properties with low loss in high-frequency to microwave-frequency range. The results show that this kind of magnetic-dielectric composites can be used in high-frequency communications for the capacitor-inductor integrating devices such as electromagnetic interference filters and antennas.