Abstract <p>Inclusion bodies (IBs) in <i>Escherichia coli</i> were once regarded as undesirable aggregates of misfolded proteins, but are now increasingly recognised as functional biomaterials. Here, we show that the N-terminal p40 domain of a lytic polysaccharide monooxygenase from <i>Caldibacillus cellulovorans</i> acts as a scaffold for producing functional inclusion bodies. This property was demonstrated across diverse proteins, including the fluorescent protein mCherry, three industrially relevant enzymes, and the antimicrobial peptide ZXR-2. The p40 domain consistently promoted IB formation under a wide range of induction conditions, and the resulting protein nanoparticles retained enzymatic activity, could be reused over multiple reaction cycles, and, when fused to ZXR-2, exhibited both antimicrobial and cytotoxic activities. Biophysical analyses revealed that IB size and morphology were influenced by cultivation parameters, highlighting the tunability of p40-mediated assemblies. Comparative analyses underscored the structural robustness of p40-driven IBs and their ability to support diverse protein contexts. While not intended for direct therapeutic use, these results emphasise the potential of p40 IBs as a platform technology for in vitro studies, biocatalysis, and other biotechnological applications. These findings establish the p40 fusion domain as a reliable scaffold for functional inclusion body production in <i>E. coli</i>, providing a foundation for future applications of IBs as versatile biotechnological tools.</p> Key points <p>• <i>p40 serves as a versatile scaffold for active protein aggregates in E. coli.</i></p> <p>• <i>Cultivation parameters modulate aggregates accumulation and physical properties.</i></p> <p>• <i>p40 fusions form recyclable nanobiocatalysts and stabilise antimicrobial peptides.</i></p>