A range of quaternised tertiary amine methacrylate-based homopolymers and copolymers were synthesised as mimics of the biopolymers implicated in biosilica formation. These synthetic polymers were evaluated for their ability to catalyse and direct the structure of silica formed by condensation of silicic acid in aqueous solution and at neutral pH. Homo- and co-polymers of differing degrees of quaternisation were studied, while some of the homopolymers also differed in their chain length. All polymers acted as catalysts for the condensation reaction, but at different rates according to their architecture and degree of quaternisation. The resulting silica–polymer hybrids were characterised fully, as were pure silicas obtained by calcination of the hybrids. Some crystallites were present in the hybrids and differences in crystal structure were observed in the calcined silicas, depending on the structure of the polymer, indicating that the polymers exert a structure-directing effect during initial silica formation. The work provides some new insights into structural factors affecting silica growth catalysed by synthetic cationic polymers.