The rhizosphere microbiome, a complex assembly of microorganisms inhabiting the root-soil interface, functions as a critical gatekeeper of plant health and soil fertility. This review synthesizes evidence that plants actively shape this community through root exudates, fostering beneficial interactions. The microbiome performs indispensable gatekeeping functions, including enhancing nutrient acquisition via phosphorus solubilization, nitrogen fixation, and siderophore-mediated iron uptake; conferring stress tolerance through induced systemic resistance and improved water dynamics; and promoting soil aggregation via fungal hyphae and bacterial exopolysaccharides. These processes underscore the microbiome's role as an extended plant phenotype, governing resource flow and pathogen defense. We argue that leveraging this knowledge is paramount for sustainable agriculture. Moving beyond conventional inputs to manage this biological system?through microbial consortia and regenerative practices?offers a transformative approach to enhance crop resilience, productivity, and long-term soil health.