Selenium (Se) has gained recognition as a critical micronutrient in agriculture, playing a pivotal role in enhancing crop resilience to biotic and abiotic stresses. This chapter, "Selenium and Stress Resilience in Crops: Mechanisms and Practical Applications," investigates the biochemical and physiological mechanisms of selenium in mitigating stress, including its regulation of antioxidant systems, improvement of nutrient uptake, and modulation of stress-related signaling pathways. The chapter also examines the synergistic and comparative efficacy of selenium alongside other ameliorating agents, such as silicon, zinc, and plant growth regulators. Practical strategies for selenium application are emphasized, including optimal methods, dosage, and timing to ensure maximum benefits in diverse cropping systems. The chapter further explores selenium’s role in managing multi-stress environments, such as drought, salinity, heavy metal toxicity, and climate-induced challenges, providing comprehensive insights into its broad-spectrum applicability. By improving crop yield and quality under stress conditions, selenium applications have the potential to reduce losses and increase profitability for farmers, contributing to improved livelihoods and economic stability. By synthesizing findings from experimental studies, field trials, and emerging technologies, this chapter bridges the gap between theoretical advancements and practical agricultural solutions. Highlighting selenium’s potential to enhance crop stress resilience, productivity, and farmer economics, the chapter offers actionable insights for researchers and agricultural practitioners. This multidisciplinary discussion underscores selenium’s role as a key component in sustainable agricultural practices aimed at addressing the challenges of modern crop production.