The interaction between light and photonic nanostructures is highly promising for light management applied to thin-film solar cells (TFSC). In this work, we introduce a strategy on conformal TFSCs on periodic nanostructures. A cost-effective self-assembly approach was used to fabricate monolayers SiO2 spherical arrays of different diameters. The structural parameters were adjusted by plasma etching procedure. Obviously, far-field light trapping properties were identified in optical performance. The conformal structure was realized in the post-deposited a-Si:H absorber layer. Photonic enhanced guided resonances were identified through finite-difference-time-domain simulation, resulted in an enhanced absorption coefficient both theoretically and experimentally. The near-field optical performance makes 500 nm SiO2 nanoparticles a promising choice for TFSC applications. To leverage the benefits of the photonic enhanced behavior, an a-Si:H solar cell with conformal nanostructure was fabricated as the first demonstration. Enhanced absorption was exhibited over the entire wavelength range. As a result, the photonic enhanced a-Si:H solar cell with conformal nanostructure based on ranged SiO2 nanospheres yielded a broadband light-management promotion, and improved the overall extemal quantum efficiency by 20% and 2.7%, respectively in comparison to the planar and textured AZO referenced. These results provide a promising platform for future development of cost-effective photonic enhanced nanostructured optoelectronic devices with efficient broadband light management.