The rapid advancement of flexible electronics has created an urgent demand for high-performance nonvolatile memory. However, conventional ferroelectric films face an intrinsic trade-off between performance and reliability in flexible applications. In this work, a high-entropy Pb0.9Ba0.1Ti0.25Hf0.25Zr0.25Sn0.25O3 (PBTHZS) ferroelectric thin film is successfully fabricated on a flexible mica substrate. Based on entropy engineering, we introduced multiple cation solid solutions to induce structural local disorder and lattice distortion at the atomic scale. This leads to a rearrangement of electron distribution in the system, and the coupling with lattice expansion enhances macroscopic polarization. As a result, the PBTHZS thin film exhibits outstanding ferroelectric properties (remnant polarization of Pr ∼62.2 μC/cm2 and maximum polarization of Pm ∼131.5 μC/cm2), stable fatigue endurance up to 108 switching cycles, minimal polarization variation across a broad temperature range of 25-120 °C, and a frequency range of 0.5-10 kHz. Furthermore, there is no apparent variation in polarization characteristics under different bending conditions. This study demonstrates that the high-entropy strategy effectively enhances the polarization performance in ferroelectric nonvolatile memory, offering a pathway for the development of next-generation flexible electronic devices.