This work explores doping with LaMnO3 on ZnO synthesized using Momordica balsamina L leaves extracts, bringing a different aspect to the photocatalytic characteristics of the nanocomposite for z-scheme heterojunction photocatalysis. ZnO/LaMnO3 exhibited a typical particle diameter of 15.78 nm and a band gap energy of 2.70 eV. Interestingly, this nanocomposite presents a highly effective photocatalyst in the degradation of malachite green (MG) under visible light exposure, with a degradation efficacy of 93.03 % within 2 h. Z-scheme heterojunction of ZnO and LaMnO3 improved the efficiency of UV light response-based ZnO photocatalyst by reducing a photorecombination of the electron-hole. The analysis of reactive oxygen species suggested that species like •O2− and h+ played a significant part in the degradation process. The photocatalyst's reusability and stability account for the observed photodegradation, indicating that the ZnO/LaMnO3 nanocomposite has preserved its superior photocatalytic performance over four cycles. This study demonstrates that photocatalytic destruction of organic contaminants in wastewater can yield remarkable outcomes. © 2025 Elsevier B.V.