<p>Aqueous zinc-ion batteries (AZIBs) have attracted considerable interest as a promising energy storage technology, owing to their intrinsic safety, high theoretical capacity, and environmental benignity. Nevertheless, their practical deployment is impeded by issues including uncontrolled dendrite growth, hydrogen evolution reactions, and anode corrosion. Regulating the zinc-electrolyte interface has thus become a central research focus. Since interfacial modification often occurs at or near the separator, the separator’s properties strongly influence overall battery performance. Although glass fiber (GF) separators are commonly employed in AZIBs due to their porous structure and good wettability, their insufficient mechanical strength increases the risk of dendrite penetration and internal short circuits. Consequently, modifying GF separators has emerged as an effective strategy for enhancing AZIB performance. This review begins by summarizing the essential requirements for separators in AZIBs, followed by a systematic overview of recent advances in GF modification using carbon-based materials, inorganic compounds, polymers, and metal-organic frameworks (MOFs). To bridge the gap toward practical application, we further examine the synergistic coupling between separators and electrolytes, incorporating discussions on cathode stability and full-cell metrics. Finally, we discuss remaining challenges and promising future directions aimed at guiding the rational design of advanced separators for high-performance AZIBs.</p>