Nonfullerene organic solar cells (OSCs) have recently made remarkable progress as one of the most promising next-generation photovoltaic technologies. Still, it is highly desirable to enhance the light harvesting for the sake of photoactive layer with a limited thickness. In this work, we developed efficient nonfullerene OSCs through incorporating hybrid plasmonic metal nanostructures (MNS) consisted of gold nanobipyramids (AuNBPs) and gold nanospheres (AuNSs). The synergistic localized surface plasmon resonance (LSPR) of hybrid MNS has been predesigned to perfectly match with the absorption range of nonfullerene photoactive layer especially in the near-infrared (NIR) region, subsequently delivering enhanced light harvesting and photo-response. The plasmonic enhancement mechanisms were systematically investigated by theoretical simulations and various experimental measurements, showing that hybrid MNS exhibited significant broadband near field enhancement and scattering effect as well as the advantage in electrical aspect to facilitate the charge extraction and transport. As a result, the power conversion efficiency (PCE) was improved from 15.46% to 16.62% for OSCs based on PM6:Y6 due to the synergistic plasmonic effect of hybrid MNS. Overall, this work paves the way for using plasmonic MNS with tunable optical properties as an alternative approach for the development of high-performance OSCs.