<p>In this study, a series of borate-based bioactive glasses with the composition [(63–x)B₂O₃–(x)ZnO–2Fe₂O₃–25SrO–10Na₂O; x = 0, 2, 4, 6, and 8&#xa0;mol%] were synthesized to investigate the effect of ZnO incorporation on structural stability, bioactivity, and antibacterial performance. X-ray diffraction (XRD) confirmed the amorphous nature of all as-prepared samples. Upon immersion in simulated body fluid (SBF), hydroxyapatite (HAp) peaks at 2θ ≈ 25.8°, 30.6°, and 36° appeared only in the ZnO-free glass, while HAp formation was completely suppressed at 6 and 8&#xa0;mol% ZnO. FTIR, SEM, and EDX confirmed the growth of HAp on the glass surface. Cytocompatibility tests were performed on human fibroblast cell lines (HFB4). The pH of the medium increased from 7.4 to 8.35 for the ZnO-free sample after 28&#xa0;days, compared to 7.80 for the 8&#xa0;mol% ZnO glass, reflecting reduced ion exchange. Weight loss analysis showed the highest solubility for the ZnO-free sample (25% after 28&#xa0;days) and the lowest for the 8&#xa0;mol% ZnO glass (4%). Dissolution dynamics (T₂/T₁ ratio) revealed accelerated release for the ZnO-free sample (1.91), stable release for the 4&#xa0;mol% ZnO glass (1.00), and inhibited release for the 8&#xa0;mol% ZnO glass (0.08). Antibacterial assays demonstrated maximum inhibition zones against <i>Bacillus sp.</i> (15&#xa0;mm), <i>Klebsiella sp.</i> (15&#xa0;mm), and <i>Pseudomonas aeruginosa</i> (17&#xa0;mm) for the ZnO-free sample, with antibacterial activity decreasing progressively as ZnO content increased. These results emphasize the dual role of ZnO: low concentrations enhance the chemical durability of bioactive glass but reduce bioactivity and antibacterial efficacy, whereas ZnO-free borate glass exhibits rapid dissolution, robust apatite formation, and strong bactericidal activity. This work provides a compositional framework for designing multifunctional borate bioglasses for bone regeneration and infection control.</p> Graphical Abstract <p></p>