Soil health reflects its capacity to sustain crop growth, productivity, and long-term environmental quality. Central to this concept is beneficial microorganisms, particularly plant growth-promoting rhizobacteria (PGPR), which fulfil essential ecological functions in the rhizosphere, the area surrounding plant roots. PGPR enhance nutrient cycling and uptake suppresses harmful phytopathogens, boosts plant immune responses, and promotes growth through the production of phytohormones and other metabolites. They also play a role in bioremediation, helping to clean polluted soils. PGPR supports plant development by increasing the availability of crucial nutrients like nitrogen, phosphorus, and iron and regulating growth and stress-related hormones, such as reducing ethylene levels through ACC deaminase activity. These microbes also contribute indirectly by protecting plants against pathogens through competition for nutrients, producing biocontrol compounds, synthesizing enzymes that break down pathogen cell walls, and triggering systemic resistance in plants. Under nutrient-deprived conditions, PGPR enhances plant fitness, bolsters stress tolerance, and can assist in nutrient cycling for better bioavailability of nutrients. This chapter highlights the mechanisms of PGPR and their potential as eco-friendly biotechnological tools for sustainable agriculture, reducing dependence on agrochemicals and encouraging more resilient, climate-adapted farming practices.