Irvingia gabonensis is an African deciduous tree species that bear edible mango-like fruits. The phytochemical screening and in vitro antimicrobial activity of the plant part extracts were evaluated. The methanol extracts of the plant were used for all the analyses. Both the qualitative and the quantitative analyses of the plant extracts were carried out using standard techniques. The susceptibility of the test organisms to the herbal extractswas done using the determination of the minimuminhibitory concentration (MIC). The significant difference was measured usingDuncan’s Multiple Range Test.Alkaloids, flavonoids, saponins, tannins, and terpenoids occurred in high levels in theleaf, stem bark, and ripe fruit peel of I. gabonensiswhereas low values of anthraquinones, phenols, and steroids were also found in all the parts. The plant extracts exhibited dose-dependent effects on the microorganisms tested. The methanol extracts of I. gabonensis parts effectively inhibited the growth of Staphylococcus aureus, Streptococcus viridians, Escherichia coli, Pseudomona saeruginosa, Salmonella enterica, Shigella sonnei, Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Fusarium oxysporum, and Rhizopus stolonifer. These extracts, therefore, showedgood antibacterial and antifungal activities at different concentrations in vitro. Hence, the pharmaceutical application of these plant parts' antimicrobial propertiesissuggested.