Plasmonic nanostructures, which exhibit notable localized surface plasmon resonance (LSPR) properties, are a promising approach for improving the efficiency of fiber-shaped dye-sensitized solar cells (FDSSCs) and flexible organic light-emitting diodes (FOLEDs). Herein, novel plasmonic nanostructure is successfully synthesized via the self-densification of gold nanoparticles (Au NPs) onto a genetically engineered M13 bacteriophage template. The synthesized Au NP-M13 bio-nanostructure show extraordinary gap-plasmon effects and significantly enhanced LSPR properties compared to randomly dispersed Au NPs for both solid-state FDSSCs (SS-FDSSCs) and FOLEDs. Briefly, a power conversion efficiency (PCE) increment of 40.7% is recorded for the Au metallic NPs-anchored M13 bacteriophage (Au NPs-M13) enhanced SS-FDSSCs; whereas an external quantum efficiency (EQE) increment of 47.2% is achieved for the Au NPs-M13 enhanced FOLEDs.