Fluorescent temperature sensing has received increasing interest in a wide range of fields, including fluid dynamics, micromechanics, and molecular cell biology. Here, a novel series of triarylboron compounds with significant thermosensitive hue transformation and high fluorescent quantum efficiency in wide temperature range is described. It is then demonstrated that fluorescent core/shell microcapsules based on one of the compounds exhibit outstanding temperature response. The microcapsules, dispersed in different liquid or solid media, can serve as highly robust, reliable, and sensitive fluorescent temperature sensors. The sensors are the first example containing a single organic luminophor with a self-reference feature that can detect on the micro- and macroscale from −30 to 140 °C. This finding may open a new avenue to the development of novel fluorescent temperature sensors.