Fungi of the genus Aspergillus promote plant growth and resistance, improve nutrient uptake, protect plants against pathogens, and increase tolerance to environmental stress. We examined the symbiosis between Aspergillus conicus and seedlings of Eucalyptus camaldulensis, a forest species widely grown in Brazil for its valuable wood and resilience. The fungus was initially identified as a contaminant of E. camaldulensis seeds growing in Murashige and Skoog basal medium. We observed that inoculated seedlings developed faster than those without the fungus. In xerophilic medium, A. conicus produced abundant spores. Analysis of the internal transcribed spacer region grouped the isolate with other A. conicus species. Seedlings grown on Murashige and Skoog medium with fungal fragments showed significant shoot growth, more leaves, and greater biomass than uninoculated seedlings. Seeds immersed in A. conicus filtrate for 24 hours showed less contamination with other fungi and a higher germination rate than those in the control group. Indole acetic acid production was below the detection limit. The fungus was endophytic, extensively colonizing the roots and being present in the stems and leaves of inoculated plants. We investigated the implications of this fungal association in silviculture and highlighted its potential benefits for plant growth and environmental stress tolerance.