Hierarchically structured polymer-clay foams comprised of sepiolite and polyvinyl alcohol (PVA) are functionalized with enzymatic and conductive properties to be employed as bioreactors and 3D bioelectrodes. The concept of nanoarchitectonics was followed in the design of this hierarchical and multifunctional cellular material through tailoring of the properties at different length scales, interfacial properties of the sepiolite fibres through adsorption of lipid molecules, bioactivity by supramolecular assembly of urease enzymes on the sepiolite-lipid bio-nanohybrid, and meso- and macroporosity controlled by incorporation of the clay fibres into a PVA matrix, and further cross-linking with borax and ice-templating. The resultant bionanocomposite foams show high structural integrity, tailored multi-level porosity, and biocompatibility which is manifested in sustained enzymatic activity. Exploratory studies show that additional doping with carbon black rendered conductive foams that could hence find usage in bioelectrocatalysis.