Temperature sensors that can operate in high-temperature and harsh environments are highly desired. However, this is a great challenge for sensing materials to operate under extreme working conditions because of oxidation and/or corrosion at high temperature. In this study, polymer-derived SiAlCN ceramics were prepared as sensing materials to overcome the abovementioned issues. A SiAlCN ceramic temperature sensor was designed and fabricated, and it performed excellent temperature-sensing properties with high accuracy, high stability, and high repeatability up to 1000 °C. Compared with traditional thermocouples, the SiAlCN ceramic sensor exhibited a faster response rate (a shorter response time). These results showed that SiAlCN ceramic is a promising sensor material for temperature measurement in high-temperature and harsh environments.