ARGONAUTE (AGO) proteins are the final effectors of small RNA-mediated transcriptional and post-transcriptional silencing pathways. Plant AGO proteins are essential for preserving genome integrity, regulating developmental processes, and in stress responses and pathogen defense. Since the discovery of the first eukaryotic AGO in Arabidopsis, our understanding of these proteins has grown exponentially throughout all the eukaryotes. However, many aspects of AGO proteins' modes of action and how they are influenced by their subcellular localization are still to be elucidated. Here, we provide an updated and comprehensive view of the evolution, domain architecture and roles, expression pattern, subcellular localization, and biological functions of the 10 AGO proteins in Arabidopsis. This review identifies and summarizes common and unique features of the expression, subcellular localization, and biological roles of the 10 ARGONAUTE proteins in Arabidopsis.