The concept of optical temperature sensing using band intensity ratio is considered as one of the most effective, self‐reference, non‐invasive, and rapid detection techniques for the local temperature in natural or engineered systems. In this work, for the first time a divalent lanthanide‐co‐doped dual‐center system, i.e., SrB₄O₇:Eu²⁺/Sm²⁺ phosphors, working as a bifunctional ratiometric sensor of temperature and pressure is employed. With temperature alterations, the Eu²⁺/Sm²⁺ luminescence intensity ratio and the emission lifetime of Sm²⁺ are significantly changed, showing unprecedentedly high relative sensitivity of 45.6 and 3.17% K^‐1, respectively. Moreover, in the pressure range from ≈10 to 40 GPa, the intensity ratio of the Eu²⁺/Sm²⁺ emissions shows strong pressure dependence and can be utilized for pressure monitoring, with high pressure relative sensitivity of ≈13.8% GPa^‐1. The superior performance indicates that the developed dual‐center Eu²⁺/Sm²⁺‐co‐doped SrB₄O₇ phosphors are promising candidates for supersensitive optical sensing applications. The findings open a new approach of designing optical temperature and pressure sensors.

Pressure is a fundamental physical parameter, so its monitoring is crucial for various industrial and scientific purposes. However, the available optical sensors allow monitoring in either low pressure or high pressure ranges. In this work, different concepts of pressure sensing are combined, and the first luminescent pressure sensor working within 9-orders of magnitude (from 10⁻⁴ to 10⁵ bar) is developed, allowing both low (vacuum) and high pressure sensing. This sensor is based on the inorganic, upconverting material (YPO₄:Yb³⁺–Er³⁺) emitting in the visible and near-infrared (NIR) ranges. For vacuum detection, the recently discovered sensing method is applied, which is based on the conversion of a luminescent thermometer into the pressure sensor. This is because of the effect of light-to-heat conversion, which is greatly enhanced under vacuum conditions, and manifested as a change in the intensity ratio of Er³⁺ thermally-coupled bands (525/550 nm). Whereas for high-pressure sensing, the emission line shift of Er³⁺ (induced by materials compression), located in the NIR spectral range, is used.