The development of new antibacterial materials is an essential global requirement. Sweetgum essential oil (SGEO) has potential biological activities including antifungal, antitermite, antioxidant, and antibacterial properties. Microencapsulation is one of the most promising ways to improve physical and chemical stability of essential oils, to prevent thermal degradation, volatilization, and undesirable reactions, and to control release of active components. In this study, it was aimed to synthesize the SGEO microcapsules as new antibacterial materials by ultrasonic-assisted complex coacervation of gelatin and gum Arabic. The coacervation between gelatin and gum Arabic as functions of gelatin:gum Arabic ratio, core material load, and ultrasonication time was investigated. The SGEO microcapsules were characterized by FESEM, FTIR, TGA, and XRD. The SGEO release of the microcapsules was investigated, and best fit was observed with the Korsmeyer-Peppas model. The antibacterial activity of the microcapsules against Gram–positive and Gram–negative microorganisms (Staphylococcus aureus and Escherichia coli) were also evaluated, and it was observed that the microcapsules had strong antibacterial activity against the two common pathogenic bacteria. All the results show that the SGEO microcapsules can be candidates as novel antibacterial materials and may be used to make contributions to antibacterial properties of different industrial products.