Microbial agents are important in improving soil quality, enhancing soil fertility, increasing crop yields, and reducing the occurrence of diseases. Their ecological functions contribute to environmental protection and the development of sustainable agriculture. Since the 21st century, academic research on microbial agents for soil improvement has deepened, yet a systematic summary of the progress in this field is lacking. This paper, based on the SCI-EXPANDED database in Web of Science and utilizing visualization tools such as VOSviewer, conducts a bibliometric analysis of research papers on microbial agents for soil improvement published between 1993 and 2023. The analysis covers publication trends, research hotspots, and their annual changes. The functional characteristics and classification of microbial agents, as well as the important ecological processes of microorganisms in soil, are systematically summarized. The results show that: 1) The number of research papers on soil improvement by microbial agents has generally increased annually both domestically and internationally, maintaining sustained research hotspots in this field. Keywords such as soil, diversity, carbon, and nitrogen have been important research hotspots over the past 30 years, with research achievements highly concentrated in a few countries such as China and the United States, and major institutions such as the Chinese Academy of Sciences; 2) This paper reviews the development trends of the research field of microbial agents for soil improvement in recent years, from aspects such as classification of microbial agents, product applications, and microbial mechanisms, and analyzes the limitations and challenges faced in the application of microbial agents for soil improvement. Several suggestions are proposed to promote the development of research on microbial agents for soil improvement.