Ceramics possess notable attributes including high-temperature stability, strong chemical tolerance, and exceptional wear resistance, rendering them highly promising for various applications. Nevertheless, the brittleness of ceramics presents a substantial hurdle in harnessing their full potential for applications in wearable devices and unconfined loading environments. In this study, an entropy-assisted strategy is proposed to realize the flexibility of Bi4Ti3O12-based dielectric nanofibers. The findings illustrate that augmented atomic configurational entropy within the nanofibers instigates favorable structural changes, including the development of refined grains and a substantial amorphous component, thereby leading to the notable improvement in the flexibility of ceramic nanofibers with functional properties. The flexible high-entropy nanofibers enable the development of a high-performance capacitive strain sensor with remarkable response sensitivity (1.62 kPa−1), wide temperature range adaptability over 25–350 °C, and excellent fatigue resistance over 3000 cycles. Importantly, this entropy-driven approach holds promise for the advancement of flexible functional ceramics, extending beyond simple oxides such as amorphous silica and alumina.