Biomaterials have a great potential to become templates for nanomaterials due to their unique dimensions and surface functionalities. Herein, we report engineered M13-virus entrapped open mouth-like Pt nanostructures by electrodeposition and explored its electrocatalytic properties for oxygen reduction reaction in an alkaline medium. Engineered M13-viruses was used as an additive to obtain biotemplated Pt nanostructures. The amine-functionalized silicate sol-gel matrix modified ITO electrode, pre-concentrated the M13-viruses from electrolyte through hydrogen bonding interaction. In solution-phase synthesis, agglomeration between the bio-mineralized M13-viruses is a serious issue for colloidal stability, the present electrodeposition approach providing solution for such issue. The present structure is having high porosity and exhibits increased electrochemically active surface area with notable structure-dependent electrocatalytic activity. • Open mouth-like biotemplated Pt nanostructures. • Encapsulation of M13-virus by Pt NSs via electrodeposition. • Increased electrochemically active surface area. • Enhanced Pt activity for ORR in alkaline medium.