Abstract: Forage millet is a dual-purpose grain and feed crop characterized by drought tolerance and strong adaptability. To investigate the effects of different ecological regions and seeding rates on its yield, quality, and ecological stoichiometry, experiments were conducted in 2023 across Hulun Buir (Inner Mongolia), Dongying (Shandong), and Zhaotong (Yunnan), with seeding densities of 16.5 and 19.5 kg∙hm². The results indicate that 1) different ecological regions significantly influences the yield and quality of forage millet. Hulun Buir and Dongying showed higher dry weights, relative feeding values, and net lactation energy than Zhaotong, which had a higher cellulose content. 2) Crude protein content was positively correlated with the relative feeding value, nitrogen content, phosphorus content, and phosphorus∶potassium ratio, but negatively correlated with cellulose content. The relative feeding value and net lactation energy were also negatively correlated with cellulose content. 3) Soil nitrate nitrogen and available phosphorus were positively correlated with yield, crude protein, and relative feeding value but negatively correlated with neutral detergent cellulose. In summary, forage millet exhibited higher yields and superior nutritional quality in the Hulun Buir and Dongying areas than in Zhaotong, indicating that these areas are more suitable for large-scale cultivation. In contrast, the yield and quality in Zhaotong were relatively low; therefore, the application of nitrogen and phosphorus fertilizers or strategies to improve nutrient-use efficiency to enhance yield and quality is required. This study provides a theoretical basis for optimizing regional cultivation and improving the quality of forage millet.