In this study for the first time, high efficient, eco-friendly and novel DyO/ZnO-Au ternary nanocomposites (Dy/ZnO-AuNCs) were prepared in presence of pomegranate fruit (PF) extract as capping and reducing agents (Dy/ZnO-AuNCs@PF). The influence of various parameters such as basic agents, reducing agents, sonication power, and sonication time were performed to reach the optimum condition. The formation of the products was characterized by FT-IR, HRTEM, XRD, FE-SEM, TEM, EDX and DRS techniques. The XRD and TEM analysis showed that the morphology and crystallite size of nanocomposites were spherical morphology and 85-90 nm, respectively. The obtained Dy/ZnO-AuNCs@PF were investigated as a nanocatalyst for degradation of erythrosine (ES) as anionic dye and basic violet 10 (BV10) as cationic dye under UV and visible light irradiations. The Dy/ZnO-AuNCs@PF exhibited higher photodegradation against ES (89.6%) and BV10 (91.3%) than pure DyO (63.1% for ES, 66.5% for BV10) and DyO/ZnO (64.5% for ES, 70.8% for BV10) under UV irradiation. It was found that gold nanoparticles have significant effect on Dy/ZnO-AuNCs@PF catalytic performance for decomposition of organic pollutants. In addition, Dy/ZnO-AuNCs@PF showed excellent in-vitro antibacterial activity against A. baumannii, S. aureus and P. mirabilis with MIC and MBC values of (5, 80 mg/ml), (5, 40 mg/ml) and (2.5, 20 mg/ml), respectively. Generally, according to its excellent antibacterial and catalytic activity, Dy/ZnO-AuNCs@PF can be used in biomedical and environmental applications.