Biodiversity losses driven by human disturbance hinder chief ecosystem functions like litter decomposition, among the most critical processes regulating forest ecosystems' carbon and nutrient cycles. Historical logging, wildfire, and ongoing livestock grazing pressure have degraded most southern temperate Nothofagus forests. Yet, the effect of forest degradation on soil fauna composition and, in turn, litter decomposition and nutrient cycling still need to be determined. This study aims to i) quantify the contribution of soil fauna to litter decomposition and mineralization of C, N, and P in Nothofagus sp. forest displaying different levels of degradation (mature, secondary, and degraded forests and a newly reforested site) and ii) assess the effect of forest degradation on the temporal composition of soil invertebrates' communities. Decomposition bags with 0.1 and 2 mm mesh were installed in long-term research plots across forest conditions. Litter decomposition and C, N, and P mineralization were estimated monthly for one year. Likewise, meso- and macrofauna's richness, abundance, and diversity were assessed bimonthly during the same period. We found that the contribution of mesofauna to decomposition was the lowest in the newly reforested site and 20 % higher in the degraded forest than in mature and secondary forests. Soil fauna substantially increased C, N, and P mineralization, particularly in the degraded forest. Differences in fauna's contribution to litter decomposition were likely related to changes in the community composition, primarily composed of detritivores in the three forested conditions and phytophagous and predators in the newly reforested site. We concluded that forest degradation modified the invertebrate community composition, and soil fauna enhances litter decomposition and nutrient mineralization in the degraded forests. In addition, our data suggest that forest degradation leads to a loss of invertebrate meso- and macrofauna orders, which alter litter decomposition processes.