Plant growth-promoting rhizobacteria (PGPRs) are essential for improving the growth, yield, and quality of medically important plants. These beneficial bacteria colonize plant roots and act through several channels using nitrogen fixation, phosphate solubilization, phytohormone generation, and the induction of systemic resistance. PGPRs enhance plant health and the biosynthesis of secondary metabolites, basic determinants of the medicinal value of plants. The increasing worldwide need for herbal treatments demands environmentally friendly approaches to optimizing the output of medicinal plants. PGPRs offer a good substitute for chemical fertilizers and pesticides by motivating plant resilience against biotic and abiotic pressures and reducing environmental impact. PGPRs have been found in many studies to help the accumulation of bioactive compounds, including phenolics, flavonoids, and alkaloids, supporting the therapeutic effects of the medicinal plants. This chapter reviews the mechanisms by which PGPRs influence medicinal plants’ metabolic pathways and development. Emphasizing their contribution to raising phytochemical enrichment, stress tolerance, and plant productivity, it draws attention to recent PGPR applications. Furthermore, the chapter covers problems and future directions in commercializing PGPR-based bioformulations for the mass production of medicinal plants. By including PGPRs in systems for manufacturing medicinal plants, we can open the road for sustainable agriculture and guarantee premium plant-based medicines. This material will be very helpful for researchers, agronomists, and practitioners seeking original ideas to enhance the growth and quality of medicinally important plants.