This concise review provides an overview of silicon nanoparticle (Si NP) synthesis techniques using agricultural waste sources like rice husks, sugarcane bagasse, and wheat straw. It covers various methods, including thermal reduction, sol-gel, microemulsion, and laser ablation. The paper highlights Si NPs versatile applications in biomedicine, energy storage, agriculture, environmental remediation, electronics, and optoelectronics, with a focus on sustainability. Additionally, it identifies research gaps in the field, emphasizing the need for improved synthesis efficiency and expanded application domains. This review offers valuable insights into the potential of agricultural waste for Si NP production and its profound impact across diverse industries.