Abstract The Hofmeister effect has attracted considerable attention for its unique ability to modulate elasticity in flexible devices. Unlike traditional approaches that often involve complex procedures and yield unstable outcomes, the Hofmeister effect enables efficient and controllable elasticity tuning through specific ion‐material surface interactions. This mechanism allows precise regulation of surface wettability, thereby facilitating dynamic adjustment of elastic properties. The review systematically summarizes the research progress on the Hofmeister effect , including its concept, underlying mechanisms, and influencing factors, with a particular focus on its applications in flexible electronics, optics, and biomedical devices. By elucidating the underlying mechanisms of ion‐induced material modulation, the review highlights the potential of the Hofmeister effect to advance the design of next‐generation smart materials. It aims to provide both a theoretical foundation and practical guidance for developing high‐performance flexible systems.