A comprehensive numerical analysis is presented to quantify the influence of hydrogen (H2) enrichment on the combustion characteristics and nitrogen oxides (NOx) formation of premixed ammonia–air (NH3/Air) flames stabilized in a swirl gas turbine combustor. Simulations were carried out for hydrogen volume fractions of 0, 5, 30, 40, and 50%, equivalence ratios of 0.85, 1.0, and 1.2, and reactant inlet temperatures ranging from 400 to 600 K. The addition of hydrogen substantially enhances flame reactivity and thermal intensity. For pure ammonia, the peak flame temperature is limited to 1958 K, whereas increasing the hydrogen fraction to 50% raises the maximum temperature to 2253 K. This enhancement is accompanied by a more compact flame structure, characterized by shorter flame lengths and a reaction zone located closer to the burner exit. Moreover, as the mixture inlet temperature increases, the chemistry is accelerated, which is evidenced by the increase in the Da number, recording 287 at 66 K compared to 117 at 400 K. The equivalence ratio and the hydrogen addition are key pillars in nitrogen oxide (NOx) formation. For the same operating conditions, the total NOx (NO+NO2+N2O) emissions increase from 1800 ppm for pure ammonia/air flame to 7500 ppm for 50% hydrogen fraction. The peak NOx emission is observed under fuel-lean operating conditions. The Peak NOx concentration of 8243 ppm is recorded at an equivalence ratio of 0.85 compared to the NOx concentration of 3797 ppm at an equivalence ratio of 1.2 (rich conditions). Overall, the results demonstrate that hydrogen-enhanced ammonia combustion can deliver stable, high-intensity flames suitable for gas turbine operation, while also revealing the inherent trade-off between improved combustion performance and increased NOx formation.