Zinc oxide nanoparticles (ZnO NPs) and manganese‐doped zinc oxide nanoparticles (Mn‐ZnO NPs) were synthesized via a cost‐effective green combustion method employing watery leaf extracts from Ipomoea Staphylina. The nanoparticles were thoroughly characterized using FT‐IR, P‐XRD, UV‐DRS, and FE‐SEM with EDX techniques. X‐ray photoelectron spectroscopy (XPS) confirmed the successful doping of Mn in ZnO NPs. Evaluation of photocatalytic efficiency revealed that ZnO NPs degraded 76 % of Congo red dye (CR), while Mn‐doped ZnO NPs exhibited a higher degradation efficiency of 92 %. The photocatalytic performance of Mn‐doped ZnO NPs surpassed that of ZnO NPs, indicating their superior photocatalytic properties. Furthermore, both ZnO and Mn‐doped ZnO NPs displayed notable antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumonia. Additionally, Mn‐doped ZnO NPs exhibited significant antioxidant activity, demonstrated by their ability to scavenge 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH⋅) free radicals. These findings suggest that biosynthesized pure and doped NPs using plant extract can be promising candidates for antibacterial and antioxidant applications in biomedical, pharmaceutical, and wastewater treatment fields.