The objectives of this study which included two experiments were to investigate the effects of dietary inclusion of sorghum grain rich in condensed tannins (CT) (18.9 g kg^–1 dry matter (DM)) on nitrogen (N) metabolism and urine nitrous oxide (N₂O) emissions of beef steers. In experiment 1, six Limousin×Luxi crossbreed steers with an initial liveweight of (245.0±18.7) kg were used as experimental animals. Three levels of sorghum grain, i.e., 0, 167 and 338 g kg^–1 DM were included in diets as experimental treatments. The animals and the treatments were randomly assigned to a replicated 3×3 Latin square design. In experiment 2, static incubation technique was used to determine the N₂O emissions of the urine samples collected in experiment 1. The results of experiment 1 showed that dietary inclusion of sorghum grain linearly increased the faecal N excretion (P=0.001), the total N excretion (P=0.010) and the faecal N to N intake ratio (P=0.021), but it did not affect the N retention and the N utilization efficiency (P>0.10). The plasma metabolomic data showed that dietary inclusion of sorghum grain increased the relative concentrations of phenolic acid (N1, N5, N10-tris-trans-p-coumaroylspermine and prenyl cis-caffeate) and carnitine (3-hydroxyisovalerylcarnitine and linoelaidyl carnitine). The results also showed that dietary inclusion of sorghum grain linearly increased the urinary urea excretion (P=0.010) and decreased the urinary excretion of purine derivatives (P=0.041) as well as the estimated rumen microbial N supply (P=0.012) based on urinary purine derivatives. The results of experiment 2 showed that including sorghum grain in the diet linearly increased the average concentrations of NH₄⁺-N (P=0.012), NO₂^–-N (P=0.009), NO₃^–-N (P=0.001) and the total inorganic N (P<0.001) in the soil enriched with urine samples. The urine sample N₂O-N flux (P=0.001), the estimated steer urine N₂O-N flux (P=0.021) and the N₂O-N to urinary N ratio (P=0.038) linearly increased with increasing inclusion of sorghum grain in the diet. In conclusion, dietary inclusion of sorghum grain containing high CT at 167 and 338 g kg^–1 DM did not affect the N utilization efficiency of steers but increased the urine N₂O-N emissions by 5.7 and 31.4%, respectively. For reducing the N₂O emissions to the environment, high levels of sorghum grain should not be included in the diet of steers.