ABSTRACT Seed quality plays an important role in the production of soybean. The objective of this study was to quantify the effects of producing region on seed chemical composition (oil, protein, and fatty acid content) and physiological quality of soybean. Twenty-eight soybean cultivars were evaluated in 2017/18 and 2018/19 crop seasons, and field trials were performed in different environments classified as high (846–963 m above sea level [asl]) or low altitude (336–480 m asl). The evaluated traits were percentage germination, accelerated aging, germination test, emergence speed index, and seed chemical composition (oil and protein contents, fatty acid profile). A significant effect of cultivar × environment interactions on all evaluated traits was observed. High-altitude environments produce soybeans with a greater protein content, and low altitudes yielded seeds with elevated oil content. Higher protein-content seeds have greater physiological potential, and seeds with higher oil content are negatively associated with physiological potential. High-altitude environments maximized the physiological quality of seeds. Linking genetics to target populations of environments ensures seed quality and benefits the entire soybean production chain.