<p>Stretchable strain sensors are a crucial component in various applications, such as wearable devices, human–machine interfaces, and soft robotics. Hence, strain sensors with low hysteresis, high fidelity, and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations. However, the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties. Herein, we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material. Based on the low-hysteresis dielectric, the prepared capacitive strain sensors exhibit ultralow electrical hysteresis (2.20% at a strain rate of 100% s⁻¹ and strain of 100%) and maintain low electrical hysteresis (4.35%) even under extremely high strain rates and large dynamic strain loads (a strain rate of 500% s⁻¹ and strain of 100%). Moreover, the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100% strain at a strain rate of 200% s⁻¹; the response curves remain nearly identical throughout these 50,000 cycles. Furthermore, the ultralow-hysteresis strain sensor was successfully applied to accurate and reliable real-time human–machine interactions, revealing its great potential in various fields, including electronic skin, flexible robotics, wearable electronics, and virtual reality.</p> Graphical abstract <p></p>