Mycorrhizae helper bacteria (MHB) are now understood to be a third essential component in the complex interaction between plants and arbuscular mycorrhizal fungus (AMF), facilitating better soil mineral uptake and providing defense against a range of biotic and abiotic environmental challenges. These bacteria, although less studied, form a robust, active community intimately linked with AMF, actively contributing to the emergence and functioning of the AMF. Even though bacteria are known to be present in the cytoplasm and spore walls of AMF spores, their impact on AMF symbiosis establishment and ecological success—by impacting spore germination, mycelial growth, metabolic diversity, root colonization, and the biocontrol of soil-borne diseases—is now being uncovered. By triggering a number of plant growth factors, MHB also improves arbuscular mycorrhizal symbiosis, enhancing plant uptake and availability of nutrients. To develop methods for encouraging mycorrhization by AMF, especially to improve soil phosphorus efficiency, it is essential to comprehend MHB’s vital metabolic signaling pathways and their role as mycorrhizal helper bacteria. As AMF bioenhancers, MHB increases agronomic efficiency as well, and formulations that combine enriched MHB populations with AMF offer a viable treatment option. This chapter endorses the use of MHB as an AMF bioenhancer in integrated nutrient management techniques for sustainable agriculture by examining the mechanisms and specificity of MHB action that favorably affect AMF development and function in mycorrhizal symbiosis.