Selenium (Se) is not only an essential micronutrient for humans and animals but also a valuable or semi-essential element for higher plants. Selenium and essential micronutrients such as iron (Fe), zinc (Zn), manganese (Mn), and magnesium (Mg) play crucial roles in plant growth, development, and overall productivity. These micronutrients influence various physiological and biochemical processes, including enzyme activation, chlorophyll synthesis, oxidative stress regulation, and nutrient uptake. The interactions between Se and these micronutrients can be synergistic or antagonistic, affecting plant metabolism, nutrient efficiency, and stress tolerance. Due to the low natural concentration of Se in soils, approximately one billion people are Se-deficient in several countries, including Brazil, Thailand, China, and Egypt. In order to raise the amount of Se in the edible portions of various crops, different forms of Se have been applied through foliar and soil application as well as seed priming. Se has been utilized to combat a number of abiotic stresses, such as cold, freezing, heat, drought, salinity, UV-B rays, and heavy metals, because of its physiological functions in higher plants. While Se is not classified as an essential element for most plants, its presence can impact the bioavailability and uptake of other micronutrients. Understanding these interactions is vital for optimizing crop nutrition, improving yield quality, and enhancing human and animal nutrition through biofortification strategies. This chapter explores the complex relationships between Se and key micronutrients, highlighting their combined effects on crop physiology and potential agronomic management practices.