Some of the earliest discovered nitrogen-fixing symbiotic prokaryotes were the ‘Rhizobia,’ microbes that associate with legume. A relatively recent group of nitrogen-fixing bacteria, beta-rhizobia plays a significant role in sustainable agriculture. Detailed insights into the relationships between beta-rhizobia and leguminous plants can be found in the phylogeny and taxonomy section on legumes. Here, we provide a discussion of recent literature focusing on the molecular aspects of beta-rhizobia-plant interactions, with potential implications for enhancing nitrogen fixation beyond nodulation processes. Furthermore, we emphasize the importance of coordinating knowledge from other disciplines into harness these beneficial microbes and advance sustainable crop farming practices. In other words, this review aims to explore the potential of beta-rhizobia and their contributions to sustainable agriculture.