<p>This present study explored the hydrothermally prepared NiFe₂O₄@g-C₃N₄ hybrid nanocomposite implemented for photocatalytic and antibacterial applications. Herein, the numerous analytical tools were employed to characterize and determine the structural, optical, morphological, surface area, electronic state, photocatalytic and antibacterial activities of the NiFe₂O₄@g-C₃N₄ heterojunction catalyst. In XRD investigation, the NiFe₂O₄@g-C₃N₄ hybrid composite exposes a cubic spinel structure and the bandgap has 2.29&#xa0;eV, which was higher than NiFe₂O₄ (2.13&#xa0;eV). Moreover, Z-Scheme photocatalytic studies were demonstrated on the NiFe₂O₄@g-C₃N₄ composite, which attains the superior degradation efficiency of 98.7% and 92.08% against Rhodamine B (Rh-B) and Methyl Orange (MO) dyes, respectively. Additionally, the antimicrobial activity of the synthesized NiFe₂O₄@g-C₃N₄ composite catalyst was explored against the gram-positive <i>Staphylococcus aureus (S. aureus)</i> and <i>gram-negative Escherichia coli (E. coli)</i> microorganisms. The output of the NiFe₂O₄@g-C₃N₄ composite was investigated for the significant region of inhibition against <i>E. coli</i>,<i> S. aureus</i>,<i> Bacillus subtilis</i>,<i> and Klebsiella pneumoniae.</i> The outputs of degradation rate and antibacterial performance of the NiFe₂O₄@g-C₃N₄ composite provided the active radicals which are involved in enhancing the electron-hole reaction. Moreover, the rate of photoexcited electron-hole pairs, accelerating the separation of photogenerated charges, and enhancing visible light absorption, arises due to the synergistic effect of the components. Finally, the outcomes of the present NiFe₂O₄@g-C₃N₄ nanocomposites are considered as potential and act as an effective catalyst for the treatment of microorganisms and dye pollutants in future.</p> Graphical Abstract <p></p>