Combining partial nitrification, granular activated carbon (GAC) filtration, and distillation is a well-studied approach to convert urine into a fertilizer. To evaluate the environmental sustainability of a technology, the operational carbon footprint and therefore nitrous oxide (N₂O) emissions should be known, but N₂O emissions from urine nitrification have not been assessed yet. Therefore, N₂O emissions of a decentralized urine nitrification reactor were monitored for 1 month. During nitrification, 0.4-1.2% of the total nitrogen load was emitted as N₂O-N with an average N₂O emission factor (EF_N2O) of 0.7%. Additional N₂O was produced during anoxic storage between nitrification and GAC filtration with an estimated EF_N2O of 0.8%, resulting in an EF_N2O of 1.5% for the treatment chain. N₂O emissions during nitrification can be mitigated by 60% by avoiding low dissolved oxygen or anoxic conditions and nitrite concentrations above 5 mg-N L^-1. Minimizing the hydraulic retention time between nitrification and GAC filtration can reduce N₂O formation during intermediate storage by 100%. Overall, the N₂O emissions accounted for 45% of the operational carbon footprint of 14 kg-CO_2,equiv kg-N^-1 for urine fertilizer production. Using electricity from renewable sources and applying the proposed N₂O mitigation strategies could potentially lower the carbon footprint by 85%.