The synthesis of a ternary nanocomposite Fe3O4/CuO-Ppy (FCPTNC) was effectively achieved via hydrothermal and in-situ chemical oxidative polymerisation techniques. FCPTNC was used as a catalyst for reducing the toxic compound 4-nitrophenol to the non-toxic compound 4-aminophenol. Additionally, it was utilised for the visible-light-induced degradation of the crystal violet (CV) dye. FCPTNC underwent characterisation using various techniques, namely X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The successful preparation of the nanocomposite was validated through analysis of its structural properties. Moreover, examining its optical properties indicated that the nanocomposite can effectively operate through visible light irradiation. The catalyst demonstrated exceptional catalytic efficacy in eliminating the targeted organic pollutants, namely 4-nitrophenol (4-NP) and crystal violet (CV). The catalyst exhibited a degradation efficiency of 97 % for CV dye within60 min. It achievedthecomplete conversion of 4-nitrophenol into its corresponding amino derivative within15 min. The calculated first-order rate constants for the reduction of 4-NP and photodegradation of CV dye were found to be in the range of 0.53–11.6 × 10−2 min−1 and 3.2–5.6 × 10−2 min−1, respectively. The magnetic catalyst exhibited efficient separation from the reaction media and was successfully recycled for up to fiveconsecutive cycles with negligible loss of catalytic activity. The work demonstrates that the FCPTNC nanocomposite has favourable characteristics, such as facilesynthesis, efficient catalytic activity, and reusability. These findings suggest that the nanocomposite possesses desirable efficiency and durability, rendering it a promising catalyst for environmental applications.