<p>L-Serine-ZnS composites were synthesized via a simple solvent casting approach by altering the quantity of added ZnS within a range of 1–5 wt%. The functions of the prepared L-Serine-ZnS composites as photocatalysts with superior performance were evaluated together with the outcomes of morphology, photoluminescence (PL) and thermal properties. The FTIR, UV–visible,¹HNMR, PL, EDX, and XRD data confirmed the viable integration of ZnS into the L-Serine in L-Serine-ZnS composites. Distinct luminescence properties, thermal stability, and morphological features of the L-Serine-ZnS composites were identified than L-Serine. FESEM micrographs exhibited irregular, nonuniform with different-shaped including sheet-like structures and spherical-shaped morphology for the composites obtained with lower loading of ZnS, while the composite morphology is changed showing a dominating spherical shape structure for higher addition. Nonetheless, for all the composite samples, the diameter remains in the range of 30–600&#xa0;nm. The XRD analysis demonstrated the average crystallite size of 4.34&#xa0;nm for the composite sample. TGA data revealed the enhanced thermal stability of composites than L-Serine. The developed composites exhibited exceptional photocatalytic activity against ciprofloxacin (CIP) than L-Serine. Comparative analysis of CIP degradation by L-Serine, ZnS, and composites with detailed kinetic study has been discussed in this work. CIP quantification by HPLC technique also confirmed the consistency of the photocatalytic degradation behavior of composites. Further, the degradation intermediates were recognized utilizing LC–MS technique provided insights into the structural changes during CIP breakdown process. These results may provide a novel understanding regarding the production of L-Serine-ZnS composites utilized as photocatalysts for the remediation of antibiotics from wastewater.</p>