Self-assembly represents a robust and powerful paradigm for the bottom-up construction of nanostructures. Templated condensation of silica precursors on self-assembled nanoscale peptide fibrils with various surface functionalities can be used to mimic biosilicification. This template-defined approach toward biomineralization was utilized for the controlled fabrication of 3D hybrid nanostructures. The peptides MAX1 and MAX8 used herein form networks consisting of interconnected, self-assembled beta-sheet fibrils. We report a study on the structure--property relationship of self-assembled peptide hydrogels where mineralization of individual fibrils through sol--gel chemistry was achieved. The nanostructure and consequent mechanical characteristics of these hybrid networks can be modulated by changing the stoichiometric parameters of the sol--gel process. The physical characterization of the hybrid networks via electron microscopy and small-angle scattering is detailed and correlated with changes in the network mechanical behavior. The resultant high fidelity templating process suggests that the peptide substrate can be used to template the coating of other functional inorganic materials.