Background and aims <p>Seasonal precipitation regimes can affect soil nitrogen (N) transformation rates, yet the underlying driving factors remain poorly studied.</p> Methods <p>To address this knowledge gap, we conducted a precipitation manipulation experiment in a subtropical forest in China from 2020 to 2022. We utilized the in situ resin-core method to assess soil physicochemical properties, microbial biomass, net nitrification rate (<i>N</i>_nit) and net N mineralization rate (<i>N</i>_min) under three treatments: control (CK), decreased precipitation by 50% during the dry season with extremely increased precipitation (≥ 50&#xa0;mm) during the wet season (IE) and decreased precipitation by 50% during the dry season with proportionally increased precipitation (≤ 20&#xa0;mm) during the wet season (IP).</p> Results <p>IE and IP significantly decreased <i>N</i>_nit (57.9% and 72.5%, respectively) and <i>N</i>_min (82.5% and 89.6%, respectively) during the dry season. However, the results were reversed during the wet season (increased by 64.3% and 79.5% and by 64.2% and 81.1%, respectively), and the effects of IP were significantly stronger than those of IE. Structural equation modeling indicated that seasonal precipitation regimes significantly affected <i>N</i>_nit and <i>N</i>_min by changing soil water content, NH₄⁺-N, microbial biomass N and soil C:N ratio. Moreover, <i>N</i>_nit and <i>N</i>_min were mainly influenced by soil physicochemical properties during the dry season, whereas microbial biomass played a more important role during the wet season.</p> Conclusions <p>Seasonal precipitation regimes can significantly affect <i>N</i>_nit and <i>N</i>_min in forest ecosystems, with the magnitude of these effects varying depending on the specific form of the seasonal precipitation regime.&#xa0;</p>