The olive tree (Olea europaea L.) is a key crop in Mediterranean and arid regions, valued for its cultural and economic importance and its natural resilience to harsh conditions. However, its cultivation is increasingly threatened by a combination of abiotic stresses—such as drought, salinity, and soil degradation—and biotic factors, particularly soilborne pathogens like Verticillium dahliae, which causes vascular wilt and significant yield losses. To address these challenges, this study evaluated the effects of three microbial consortia, each composed of selected bacterial and yeast strains with plant-beneficial traits, on early olive plant development and disease resistance under sterile, climate-controlled conditions. The bacterial components, derived from the phylum Bacillota (Oceanibacillus, Schouchella, Lentibacillus), are known for stress tolerance, enzymatic activity, and antagonism against pathogens. Each consortium also included strains of the osmophilic yeast Zygosaccharomyces, capable of secreting bioactive compounds with antifungal properties. Over a 90-day period, inoculated olive saplings were assessed for growth (shoot and root biomass, plant height), physiological performance (chlorophyll content, root-to-shoot ratio), and response to V. dahliae infection. All consortia significantly enhanced plant growth compared to untreated controls, with one formulation increasing root biomass by up to 40% and improving chlorophyll levels. In pathogen-inoculated plants, microbial treatments reduced disease severity, delayed symptom onset, and significantly lowered pathogen DNA concentrations in root tissues, as confirmed by qPCR. These results highlight the potential of microbial consortia as effective biostimulants and biocontrol agents in olive cultivation. Their use could reduce dependence on chemical inputs and improve productivity and resilience in both conventional and organic farming systems. Field trials are recommended to validate these findings under diverse environmental conditions