Plants interact with many different bacteria at various stages of their life. A mutualistic relationship between a plant and an endophytic bacterium occurs when a plant provides a safe habitat and a secure food supply to the microbe and it, in return, benefits the plants’ capacity to function in its environment. In this study, corn sap was screened for the diversity and functionality of culturable bacterial endophytes, and a total of 437 bacterial endophytes were isolated, identified, and characterized for their possible role as biofertilizers and biocontrol agents. The growth promoting traits that were characterized included siderophore production, phosphate and zinc solubilization, nitrogen fixation, indole acetic acid production, and antifungal activity against several plant pathogens. Most isolates (71.8%) were found to fix nitrogen and solubilize phosphate (66.8%), close to half (42.5%) could solubilize zinc, and 28.3% of the corn bacterial endophytes could sequester iron. Most isolates (77.3%) displayed antifungal activity, and 186 of the 437 isolates tested were found to promote plant growth in a gnotobiotic assay. These results suggest that growth promotion from these bacterial endophytes is the outcome of multiple biochemical and microbiological mechanisms.