We report the synthesis of silicon oxycarbonitride ceramic-graphene oxide (SiCNO-GO) composites by using polyvinylsilazne (PVSZ) and GO as precursors through cross-linking processes, in which GO organizes into microspheres in the SiCNO matrix. The formation of GO microspheres significantly enhances the electrical conductivity of SiCNO. The electrical resistivity of SiCNO-GO composites shows a negative temperature coefficient in the range from 25 degrees C to 600 degrees C. We demonstrate the application of SiCNO-GO composites as the functional component of high-temperature sensors.