Extreme temperatures, drought, and salinity are among the most detrimental abiotic stressors limiting global plant productivity, and their frequency has intensified under climate change. These escalating pressures underscore the need for sustainable biological strategies that enhance plant resilience to climate-induced abiotic stresses. Plant growth-promoting rhizobacteria (PGPR) have emerged as a promising, eco-friendly solution due to their ability to optimize rhizospheric processes that strengthen plant adaptive capacity. PGPR improve nutrient acquisition, maintain ionic homeostasis, modulate phytohormone signaling, and regulate ethylene levels through ACC deaminase activity. They also stimulate antioxidant defenses, promote osmolyte and exopolysaccharide synthesis, and enhance root system development—key traits that collectively alleviate drought, salinity, and heat stress. Recent research demonstrates that co-inoculation, multi-strain microbial consortia, and synthetic communities designed using multi-omics approaches significantly enhance PGPR stability, colonization, and functional effectiveness under field conditions. Additionally, nanotechnology-enabled formulations and smart delivery systems are emerging as innovative tools to improve PGPR survival and targeted release in harsh environments. This review synthesizes current insights into PGPR-mediated stress mitigation, highlights technological innovations that support their application, and outlines pathways for integrating PGPR into climate-resilient, sustainable agricultural systems to safeguard crop productivity amid escalating environmental stress.