Biodegradable and biocompatible organic polymers play a pivotal role in designing the next generation of wearable smart electronics, reducing electronic waste and carbon emissions while promoting a toxin-free environment. Herein, an electrospun fibrous polyhydroxybutyrate (PHB) organic mat-based, energy-autonomous, skin-adaptable temperature sensor is developed, eliminating the need for additional storage or circuit components. The electrospun PHB mat exhibits an enhanced β-crystalline phase with a β/α phase ratio of 3.96 using 1,1,1,3,3,3-hexafluoro-2-propanol as a solvent. Solvent and film processing techniques were tailored to obtain high-quality PHB films with the desired thickness, flexibility, and phase conversion. The PHB mat-based temperature sensor (PHB–TS) exhibits a negative temperature coefficient of resistance, with a sensitivity of - 2.94%/°C and a thermistor constant of 4676 K, outperforming pure metals and carbon-based sensors. A triboelectric nanogenerator (TENG) based on the enhanced β-phase PHB mat was fabricated, delivering an output of 156 V, 0.43 µA, and a power density of 1.71 mW/m2. The energy-autonomous PHB–TS was attached to the index finger to monitor temperature changes upon contact with hot and cold surfaces, demonstrating good reliability and endurance.