Agrotoxins, including agrochemical residues and mycotoxins, present serious environmental and health hazards due to their persistence and toxicity. While pesticides and fertilizers are vital for enhancing agricultural productivity, their extensive use leads to the accumulation of harmful residues in the environment. Additionally, fungal toxins contribute to heightened health risks, making the detection of agrotoxins a critical necessity. Current detection methods are limited, emphasizing the need for efficient, rapid, and on-site monitoring solutions. Nanotechnology-based sensors, particularly surface plasmon resonance (SPR) nanosensors, have emerged as promising tools for tackling this challenge. Enhanced by nanomaterials (NMs), SPR sensors offer significant advantages, including ease of use, label-free detection, miniaturization, high sensitivity, specificity, and real-time capabilities. These features make them well-suited for detecting elusive agrotoxins across diverse agricultural applications. However, despite their potential, a comprehensive review of recent advancements in nanomaterials designed for SPR nanosensors targeting agrotoxin residues in soil is lacking. This chapter addresses this gap by providing an overview of the nanomaterials employed in SPR nanosensors for agrotoxin detection. It also highlights the existing challenges, such as sensor stability, selectivity, and real-world applicability, while exploring future prospects for leveraging nanosensors to mitigate agrotoxin risks and enhance agricultural sustainability.