Contemporary agriculture aims to produce food and livestock with minimal environmental impact. Several recent technologies have the ability to support agriculture in providing food for ever-increasing populations with minimal adverse impact on the surrounding ecosystem. Nanotechnology is one such promising technology that can support the development of sustainable agriculture. Algae have emerged as a living factory for the environment friendly synthesis of nanoparticles (NPs). They have the ability to accumulate metals and remodel them into NPs. These NPs have tremendous potential to support agricultural sustainability by improving crop growth and nutrient uptake, enhancing disease resistance, and ameliorating abiotic stress tolerance. However, the scope of algae-based NPs in developing sustainable agriculture has remained an unexplored research area in the literature. The present chapter summarizes recent advancements and future perspectives of algal NPs in sustainable agriculture. The chapter also discusses the mechanism of NPs synthesis, factors affecting the algae-based synthesis of NPs, the effect of NPs on crop plants, and the application of NPs in agriculture.