This study conducted a comprehensive comparative genomics analysis of 278 *Bradyrhizobium* strains to investigate their genetic diversity and functional properties, particularly in relation to symbiotic nitrogen fixation. The pan-genome of *Bradyrhizobium* consisted of 84,078 gene families, with 824 core genes and 42,409 accessory genes. Core genes were primarily involved in essential cellular processes, while accessory genes served diverse functions, including nitrogen fixation and nodulation. Three distinct genetic profiles were identified based on the presence/absence of gene clusters related to nodulation, nitrogen fixation, and secretion systems. Most strains from soil and non-leguminous plants lacked major nif/nod genes and were evolutionarily more closely related. The study also explored the distribution of nitrogen fixation and nodulation genes, finding that the majority of strains from legumes had both nif and nod gene clusters, suggesting their potential as rhizobial inoculants. Additionally, the study highlighted the plasticity of *Bradyrhizobium* genomes and the diversity of carbon fixation genes within the genus, which may contribute to its agricultural and environmental applications. The findings provide a detailed understanding of the genetic characteristics and nitrogen fixation profile of *Bradyrhizobium*, contributing to the genus's agricultural research and applications.This study conducted a comprehensive comparative genomics analysis of 278 *Bradyrhizobium* strains to investigate their genetic diversity and functional properties, particularly in relation to symbiotic nitrogen fixation. The pan-genome of *Bradyrhizobium* consisted of 84,078 gene families, with 824 core genes and 42,409 accessory genes. Core genes were primarily involved in essential cellular processes, while accessory genes served diverse functions, including nitrogen fixation and nodulation. Three distinct genetic profiles were identified based on the presence/absence of gene clusters related to nodulation, nitrogen fixation, and secretion systems. Most strains from soil and non-leguminous plants lacked major nif/nod genes and were evolutionarily more closely related. The study also explored the distribution of nitrogen fixation and nodulation genes, finding that the majority of strains from legumes had both nif and nod gene clusters, suggesting their potential as rhizobial inoculants. Additionally, the study highlighted the plasticity of *Bradyrhizobium* genomes and the diversity of carbon fixation genes within the genus, which may contribute to its agricultural and environmental applications. The findings provide a detailed understanding of the genetic characteristics and nitrogen fixation profile of *Bradyrhizobium*, contributing to the genus's agricultural research and applications.