Sodium-ion batteries (SIBs) present a burgeoning alternative to lithium-ion batteries (LIBs) owing to their abundance, cost-effectiveness, and inherent safety. The additional allure of flexibility further underscores their potential in wearable electronics and applications demanding conformability. This review critically assesses the recent advancements in flexible SIBs, scrutinizing electrode materials, electrolytes, and device architecture. Key achievements and enduring hurdles are meticulously examined for each segment, highlighting current strengths and future pathways. Promising applications and forthcoming research directions are also explored, outlining the trajectory of this burgeoning technology.