A sourceless sapphire fiber extrinsic Fabry-Perot interferometer for ultrahigh temperature sensing is developed. A sapphire wafer is mounted on the tip of a sapphire fiber as the Fabry-Perot cavity. The interference signal is generated by the thermal radiation that transmits through the wafer and is guided to a spectrometer by a sapphire and then a silica fiber. The entire sensor system is compact and low cost. The sensor was experimentally tested up to 1593°C, and a resolution around 1°C was achieved.