In this work, CeO2/LaMnO3 heterojunction was constructed via decoration of LaMnO3 spheres with CeO2 flowers via applying hydrothermal technique. The structural, composition and optical features of the as-obtained samples were systematically characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman, UV–Vis diffuse reflectance and photoluminescence spectroscopy techniques. The characterizations revealed that the formation of heterojunction catalyst with the crystal phases of LaMnO3 and CeO2 materials. The presence of Ce3+ and Ce4+ oxidation states was also confirmed which assisted the redox cycle in Fenton-like photocatalytic reaction. The photocatalytic activities of the as-prepared catalysts were investigated for photodegradation of sunset yellow food dye under peroxymonosulfate (PMS)-activated visible light system. As expected, compared to bare LaMnO3 (51% degradation), the CeO2/LaMnO3 heterojunction displayed boosted the photocatalytic performance (96.8% degradation). Such an enhancement was mainly attributed to the formation of p-n heterojunction, which supressed the recombination rate and facilitated the charge transfer efficiency. Radical trapping tests demonstrated the degradation mechanism in which the superoxide and sulphate radicals were found as active substances in the reaction. The proposed CeO2@LaMnO3/Vis/PMS catalytic system exhibited well degradation performance towards other dye and antibiotic molecules. This work provides an important reference for the development of heterojunction materials in Fenton-like photocatalytic systems for eliminating different kinds of pollutants in wastewater.