Switchgrass (Panicum virgatum L.), a warm-season perennial grass traditionally used for forages, has gained traction as a green energy source due to its potential as a bioenergy feedstock. This biofuel alternative reduces reliance on fossil fuels, potentially mitigating greenhouse gas emissions. Cultivar improvement is crucial for expanding switchgrass biofuel use. Seed yield should be a target for improvement since switchgrass is commercially grown by seed. In this study, quantitative trait loci (QTL) for seed yield were identified within two pseudo-testcross populations: a cross between the lowland AP13 genotype and coastal B6, and a cross between the upland VS16 genotype and coastal B6. The progenies were compared over three years and the data was used to identify significant QTL associations with seed yield. Overall, 25 QTL were identified, 16 within the AB population and 9 in the BV population. These findings offer valuable insights into the potential seed yield of Switchgrass.