Arbuscular mycorrhizal fungi (AMF) can actively suppress nitrous oxide, one of the most powerful climate-warming gases, by rewiring how wetlands process nitrogen. In constructed wetlands, plant–fungus symbiosis cut average N₂O emissions by ~18.5% and peak fluxes by ~24.5% by enriching low–N₂O-yield nitrifiers and boosting nosZ-driven denitrification, the final step that converts N₂O into harmless N₂. The results reveal mycorrhizal fungi as metabolic climate regulators, not passive soil partners, capable of steering whole microbial networks toward lower greenhouse-gas output.