In Saskatchewan, red clover (Trifolium pratense L.) is often grown for seed production. However, there is no recognized or data supported seeding rate for seed production of red clover in Saskatchwan. The objectives of this study were to identify an optimal seeding rate for seed production and biological nitrogen fixation (BNF) and to examine their relationships under semi-arid conditions. This experiment was conducted under field conditions using six different seeding rates (0.5, 2.5, 4.5, 6.5, 8.5, and 10.5 kg ha⁻¹) at Melfort and Clavet, SK in 2018 and 2019, and seed yield, biomass, plant density, and BNF were measured. In our study, red clover was able to compensate for the range of seeding rates between 2.5 and 10.5 kg ha⁻¹ without seed yield loss and BNF reduction, whereas biomass production and BNF were higher at 4.5 kg ha⁻¹ seeding rate than in 0.5 kg ha⁻¹ at Melfort, but no seeding rate effects were found at Clavet. Regardless of location, biomass was always positively correlated with BNF. However, no association was found between seed yield and BNF. Our results suggest that 4.5 kg ha⁻¹ is ideal for seed production, BNF and biomass production of red clover in Saskatchewan.