Synthesis of photocatalysts with activity for the degradation of a broad range of pollutants is of significant importance for environmental remediation. In this article, lanthanum-doped zinc oxide (La-ZnO) nanostructures containing different dopant levels (0.1-0.9 wt%) were prepared via a co-precipitation approach and systematically evaluated for their physicochemical, photocatalytic, and antibacterial features. Structural and optical analyses including X-ray diffraction (XRD), Ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), Raman spectroscopy and photoluminescence spectroscopy (PL), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) verified the efficient inclusion of La3+ within the lattice of ZnO, causing lattice distortion, increased light absorption, and inhibiting electron-hole recombination. Photocatalytic performance was tested under acidic medium (pH 5) with a UV-C light source of 32 W against different pollutants, namely Methylene Blue (MB), Reactive Red 120 (RR 120), Acid Black 1 (AB 1), and ciprofloxacin (CIP). Among all the compositions studied, the 0.6 wt% La-ZnO catalyst performed the most favourably, where the degradation of MB and AB 1 was most significant (achieving nearly 100% degradation) within 120 min under UV-C irradiation at pH 5, while RR 120 and CIP showed a degradation efficiency of approximately 71% and 55% at 120 and 150 min, highlighting the pollutant-specific nature of La doping. Scavenger experiments showed that hydroxyl (center dot OH) radicals and superoxide (O2 center dot-) species were the most important reactive oxygen species involved in pollutant degradation, while GC-MS certified sequential mineralization mechanisms. Along with the photocatalysis, La-ZnO nanostructures were found to exert pronounced antibacterial activity against Gram-positive and Gram-negative microorganisms. The optimized catalyst showed stable behaviour and effective reusability in consecutive cycles, which is characteristic of its real-world applications. This comparative overview gives highest priority to La doping as a useful strategy for the modulation of the electronic and structural features of ZnO towards achieving wide-spectrum photocatalysis and antimicrobial activity. The paper presents La-ZnO as a flexible and green material based on dye and antibiotic pollutant removal under UV-C irradiation.