Chronically elevated nitrogen (N) deposition has led to severe nutrient imbalance in forest soils. Particularly in tropical and subtropical forest ecosystems, increasing N loading has aggravated phosphorus (P) limitation of biomass production, and has resulted in elevated emissions of nitrous oxide (N₂O) and reduced uptake of methane (CH₄), both of which are important greenhouse gases. Yet, the interactions of N and P and their effects on greenhouse gas emissions remain elusive. Here, we report N₂O and CH₄ emissions together with soil N and P data for a period of 18 months following a single P addition (79 kg P ha⁻¹, as NaH₂PO₄ powder) to an N-saturated, Masson pine-dominated forest soil at TieShanPing (TSP), Chongqing, south-western (SW) China. We observed a significant decline in both nitrate (NO₃⁻) concentrations in soil water (5 and 20 cm depths) and in soil N₂O emissions, following P application. We hypothesise that enhanced N uptake by plants in response to P addition, resulted in less available NO₃⁻ for denitrification. By contrast to most other forest ecosystems, TSP is a net source of CH₄. P addition significantly decreased CH₄ emissions and turned the soil from a net source into a net sink. Based on our observation and previous studies in South America and China, we believe that P addition relieves N inhibition of CH₄ oxidation. Within the 1.5 years after P addition, no significant increase of forest growth was observed and P stimulation of forest N uptake by understorey vegetation remains to be confirmed. Our study indicates that P fertilisation of N-saturated, subtropical forest soils may mitigate N₂O and CH₄ emissions, in addition to alleviating nutrient imbalances and reducing losses of N through NO₃⁻ leaching.