Plant production greatly depends on the efficient transport and recycling of minerals, with particular emphasis on trace elements such as selenium (Se), which play a crucial role in plant growth and development. Selenium performs various important functions in plants such as offering protection against oxidative stress resulting from reactive oxygen species. Additionally, Se is also essential for photosynthesis process which enhances nutrient uptake by plants, improving their overall development. Plants are essential sources of organic selenium as they have the ability to accumulate inorganic selenium or its metabolites and store it in organic forms. Organic selenium species in general, including selenoamino acids like Se-methylselenocysteine (MSC), selenocystine (SeCys2), and selenomethionine (SeMet) may give more bioactivities while being less toxic than inorganic selenium such as selenite (Se IV) and selenate (Se VI). Consequently, selenium-enriched plants may be utilized as human food to mitigate deficient issues and provide health advantages. The biological implications and toxicity of selenium compounds in humans are contingent upon their chemical forms and dosage levels consumed. The concentration and chemical forms of Se in plants are mostly dictated by the accumulating capacity of the plant species. In comparison to other plants, the Brassica family and cereal grains have a high ability for accumulation and the storage of substantial organic Se compounds in their cells. Selenium-enriched plants shows biological activities including anti-diabetes, antioxidant and anticancer activities. The bioaccessibility of selenium in processed foods can vary, stressing the necessity for appropriate biofortification measures to provide sufficient Selenium intake via diet. This book chapter explores the versatility of Se, highlighting its importance as an essential nutrient and accumulation profile in crops and processed foods. Although Se integration offers promising prospect for agricultural applications, further research is still needed to fully understand its effects, fate, and potential risks. Assessing the toxicity of Se to plants, animals, and the environment is crucial for their safe and sustainable implementation. This manuscript synthesizes current knowledge regarding the behavior and effects of Se across varied ecosystems and introduces a “soil to spoon” framework to outline future research avenues.