<p>This research outlines the successful synthesis of a new and novel ternary heterojunction photocatalyst, CaFe₂O₄/ZnSe/TiO₂ for efficient degradation of dye under visible light irradiation. The study also provides insights into the morphology, structure, chemical composition of the composite and the mechanistic understanding behind the efficient photocatalytic activity. Results of scavenger experiments reveal hydroxyl radicals, superoxide radicals, and holes are the main reactive species involved in the degradation process. The hydrophilic nature of composite complimented in degradation of dye. Moreover, the composite showed outstanding stability and reusability throughout seven cycles. Germination studies using Cicer arietinum demonstrated the non-toxicity of the treated water, making it suitable for horticulture use. Therefore, the synthesized composite has potential use in environmental cleanup and wastewater management.</p> Graphical abstract <p></p>