Photosynthesis, the foundation of agricultural productivity, is a process ripe for enhancement through nanotechnology. This chapter explores the cutting-edge applications of engineered nanomaterials (NMs) in boosting photosynthetic efficiency, focusing on their mechanisms of action, benefits, and potential risks. We examine how metallic nanoparticles, carbon-based nanomaterials, and quantum dots interact with plant photosynthetic machinery through multiple pathways—including light absorption optimization, electron transport facilitation, reactive oxygen species (ROS) scavenging, and chloroplast protection. The discussion highlights evidence-based examples where nanomaterials have increased quantum yield, improved CO2 fixation, and enhanced stress resilience in various crop species. We also address critical considerations such as nanomaterial biocompatibility, optimal concentration ranges, and application methods (foliar vs. root exposure). Emerging innovations in nanobionics, where nanomaterials are engineered to augment or even surpass natural photosynthetic capabilities, are explored as potential game changers for future agriculture. The chapter further discusses the environmental implications of nanomaterial use in agriculture, emphasizing the need for sustainable designs and rigorous safety assessments. By bridging fundamental research with practical applications, this chapter provides a comprehensive resource for scientists and agronomists seeking to harness nanotechnology for sustainable intensification of crop production. The insights presented here aim to guide future research toward developing effective, safe, and scalable nanomaterial-based solutions to meet global food security challenges in an era of climate change.