This review article explores how soil fauna influence the formation and stabilization of labile (particulate organic matter, POM) and stabilized (mineral-associated organic matter, MAOM) soil organic matter (SOM). The study identifies three major mechanisms by which soil fauna affect SOM: transformation, translocation, and grazing on microorganisms. These processes alter factors essential for POM and MAOM formation, including organic matter quantity and decomposability, soil mineralogy, and microbial community composition. Understanding these mechanisms is crucial for advancing concepts, models, and policies related to soil organic matter and managing soils as carbon sinks, nutrient stores, and food providers. Soil fauna are abundant, diverse, and active in soils worldwide, even in extreme environments. They affect various soil biophysicochemical properties, including microbial diversity, soil structure, and nutrients, through ingestion, transformation, and grazing. These processes are essential in driving biogeochemical cycles and may significantly affect SOM dynamics. However, knowledge of soil fauna's role in SOM formation and stabilization is limited, except for earthworms. The review highlights that soil fauna can influence both pathways of MAOM formation: the microbial pathway, where microbial biomass becomes necromass and interacts with minerals, and the direct sorption pathway, where dissolved organic matter sorbs onto mineral surfaces. Soil fauna may affect these pathways by altering organic matter quantity, quality, and location, microbial biomass and community composition, and generating dissolved organic matter through processing of litter and other organic matter. The study emphasizes the need for further research to quantify the contributions of soil fauna to POM and MAOM formation through the three major processes, how interactions among faunal taxa or within whole communities alter this contribution, and whether these contributions remain stable under varying environmental conditions. The review recommends controlled laboratory experiments, standardized fractionation schemes, and stable isotope labeling to trace and quantify bioturbation rates and C flows among different SOM pools. These approaches can provide mechanistic insights into the effects of soil fauna on SOM dynamics, which can be upscaled to field settings to assess the relevance of land use, climate change, and other environmental factors. The study also highlights the importance of soil fauna in regulating POM and MAOM formation through organic matter transformation, translocation, and grazing on microbial communities, and calls for interdisciplinary cooperation to address this major research frontier.This review article explores how soil fauna influence the formation and stabilization of labile (particulate organic matter, POM) and stabilized (mineral-associated organic matter, MAOM) soil organic matter (SOM). The study identifies three major mechanisms by which soil fauna affect SOM: transformation, translocation, and grazing on microorganisms. These processes alter factors essential for POM and MAOM formation, including organic matter quantity and decomposability, soil mineralogy, and microbial community composition. Understanding these mechanisms is crucial for advancing concepts, models, and policies related to soil organic matter and managing soils as carbon sinks, nutrient stores, and food providers. Soil fauna are abundant, diverse, and active in soils worldwide, even in extreme environments. They affect various soil biophysicochemical properties, including microbial diversity, soil structure, and nutrients, through ingestion, transformation, and grazing. These processes are essential in driving biogeochemical cycles and may significantly affect SOM dynamics. However, knowledge of soil fauna's role in SOM formation and stabilization is limited, except for earthworms. The review highlights that soil fauna can influence both pathways of MAOM formation: the microbial pathway, where microbial biomass becomes necromass and interacts with minerals, and the direct sorption pathway, where dissolved organic matter sorbs onto mineral surfaces. Soil fauna may affect these pathways by altering organic matter quantity, quality, and location, microbial biomass and community composition, and generating dissolved organic matter through processing of litter and other organic matter. The study emphasizes the need for further research to quantify the contributions of soil fauna to POM and MAOM formation through the three major processes, how interactions among faunal taxa or within whole communities alter this contribution, and whether these contributions remain stable under varying environmental conditions. The review recommends controlled laboratory experiments, standardized fractionation schemes, and stable isotope labeling to trace and quantify bioturbation rates and C flows among different SOM pools. These approaches can provide mechanistic insights into the effects of soil fauna on SOM dynamics, which can be upscaled to field settings to assess the relevance of land use, climate change, and other environmental factors. The study also highlights the importance of soil fauna in regulating POM and MAOM formation through organic matter transformation, translocation, and grazing on microbial communities, and calls for interdisciplinary cooperation to address this major research frontier.