Conventional agriculture plays a vital role in meeting the increasing demands for food which result from the continuous rising of the human population. Nowadays farmers use more and more amounts of chemical fertilizers and pesticides which have a bad influence on soil quality, the ecosystem, and the health of humans. Hence, it is important to explore other approaches to decrease the application of chemical fertilizers and enhance crop productivity. Inoculation of the crop with plant growth promoting rhizobacteria (PGPR) to augment sustainable agriculture production is another strategy that is eco-friendly and could be carried out in the long run.  PGPR is a group of bacteria able to colonize the root of plants and increase their growth and yield. They help in increasing water absorption, suppress pathogens, and also enhance the uptake of nutrients form soil. Biochemical applications by which rhizobacteria can stimulate the growth of plants were discussed in this article; (i) bio-stimulants: represented by particular phytohormones synthesized by PGPR for e.g. auxins or indole acetic acid (IAA), cytokinins, gibberellic acid (GA) and ethylene, (ii) biofertilization: through helping the uptake of many nutrients from the environment e.g. biological nitrogen fixation, phosphate solubilization and production of siderophore, (iii) bioprotectants or biocontrol: by preventing plant diseases through antibiotic, lytic enzymes and/or hydrogen cyanide (HCN) production.