This comprehensive review explores the prevalence, diversity, and potential applications of non-rhizobial endophytic bacteria in legume nodules. Legumes form symbiotic associations with soil bacteria, primarily from the *Rhizobiaceae* family, which convert atmospheric nitrogen into plant-assimilable form. However, non-rhizobial endophytic bacteria, such as *Bacillus* and *Pseudomonas*, also reside in these nodules, contributing to various plant growth-promoting properties (PGPs). These bacteria enhance plant growth through mechanisms like phytostimulation, biofertilization, biocontrol, and stress tolerance. The review highlights that *Glycine max* is the primary host for these endophytes, followed by *Vigna radiata*, *Phaseolus vulgaris*, and *Lens culinaris*. Co-inoculation with both rhizobia and non-rhizobia has shown synergistic effects on plant growth, yield, and nodulation, particularly under stress conditions. The review also discusses the ecological roles and benefits of nodule endophytes, emphasizing their potential in sustainable agriculture and addressing the challenges of chemical-intensive agriculture.This comprehensive review explores the prevalence, diversity, and potential applications of non-rhizobial endophytic bacteria in legume nodules. Legumes form symbiotic associations with soil bacteria, primarily from the *Rhizobiaceae* family, which convert atmospheric nitrogen into plant-assimilable form. However, non-rhizobial endophytic bacteria, such as *Bacillus* and *Pseudomonas*, also reside in these nodules, contributing to various plant growth-promoting properties (PGPs). These bacteria enhance plant growth through mechanisms like phytostimulation, biofertilization, biocontrol, and stress tolerance. The review highlights that *Glycine max* is the primary host for these endophytes, followed by *Vigna radiata*, *Phaseolus vulgaris*, and *Lens culinaris*. Co-inoculation with both rhizobia and non-rhizobia has shown synergistic effects on plant growth, yield, and nodulation, particularly under stress conditions. The review also discusses the ecological roles and benefits of nodule endophytes, emphasizing their potential in sustainable agriculture and addressing the challenges of chemical-intensive agriculture.