Long term nitrous oxide (N₂O) measurements remain scarce for aerobic granular sludge (AGS) systems. This study presents the first three year full scale N₂O monitoring campaign at the Nereda® installation in Panheel (NL), quantifying emissions in both the liquid phase and reactor off gas. The results reveal a clear and recurring seasonal pattern, with N₂O peaks consistently occurring in summer—distinct from conventional activated sludge systems, which typically peak in spring. Leveraging the two reactor configuration, six targeted mitigation strategies were systematically tested under identical operating conditions. These strategies addressed various stages of the nitrogen cycle and included optimized pre denitrification, adjusted aeration regimes, enhanced mixing during post denitrification, and improved intermittent aeration control. Individually, several interventions demonstrated measurable emission reductions; in combination, they achieved a cumulative N₂O reduction exceeding 45%, with also improvements in effluent quality. The rapid convergence of emission profiles between reactors after adopting optimized settings further highlights the strong operational leverage in controlling N₂O formation. Overall, the findings demonstrate that substantial and stable N₂O mitigation is achievable in full scale AGS systems through integrated process control.