The constant increase in the number of sustainable products on the global markets demands new biotechnological processing strategies such as the purification and recovery of biocatalysts. Superparamagnetic iron oxide nanoparticles exhibit excellent recovery properties as carrier materials in enzyme catalysis. We present the simple and fast electrostatic assembly of cellulase (CEL) and low-priced silica-coated magnetic nanoparticles, which demonstrates stable enzyme bonding and excellent colloidal stability. The high CEL loading (0.43 g g⁻¹), without leaching of biocatalyst and high recovery yields (75 %), could be sustained over ten magnetic recycling steps. The highlight of this study is the preservation of a high enzymatic activity and, therefore, the outstandingly high lifecycle stability.