This communication describes a novel environmentally friendly method to prepare bioactive urease/ZnFe₂O₄ nanocomposites through a one-pot and one-step process. The synthetic procedure is triggered through a biological mineralization process of decomposition of urea catalyzed by urease. During the growth of ZnFe₂O₄, urease molecules are immobilized by original ZnFe₂O₄ nanoparticles. As a consequence, the bioactive urease/ZnFe₂O₄ nanoparticle composites are assembled. This simple route is expected to endow the bioactive nanocomposites with new properties for various interesting fields.