A prototype single‐mode fiber‐based ultrahigh pressure remote sensor based upon a Fizeau cavity using a dual‐wavelength coherence reading technique with built‐in temperature compensation has been constructed capable of remote operation at distances up to 10 km. A separate fiber‐based temperature sensor with similar cavity length was incorporated into the pressure probe to allow the pressure measurement to be corrected for the temperature dependence of the pressure sensor. A range to resolution of ∼1.67×104:1 and an overall measurement accuracy of ∼±0.69% over a pressure range of ∼1000 bar have been achieved. This system represents a practical approach for industrial applications, such as measuring the pressure of an oil well.