Background: A green and efficient process, free from toxic solvents, was employed to prepare an alpha-mangostin-rich extract. Conventional techniques like maceration and heat reflux extraction are recognized for their time-intensive nature, as well as the requirement for significant quantities of organic solvents. This innovative process not only reduces energy consumption but also streamlines production steps, providing a more sustainable alternative in herbal medicine preparation. Purpose: The purpose of the study was to compare the antibacterial activities of alcohol disinfectants and alpha-mangostin extract-containing disinfectants against tested microorganisms. Methods: The alpha-mangostin-rich extract was obtained from dried powders of Garcinia mangostana pericarps utilizing the microwave-assisted extraction method with polyethylene glycol 400 (PEG 400). The alpha-mangostin content in the resultant extract was determined through the high-performance liquid chromatography (HPLC) method. Additionally, a broth microdilution method was utilized to investigate the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of each compound against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus pseudintermedius. Results: According to a microdilution method, the disinfectant comprising isopropanol (50% and 70%) with 1% alpha-mangostin extract demonstrated antibacterial effectiveness against both MRSA and S. pseudintermedius. The MICs and MBCs were observed within dilutions ranging from 1:64 to 1:512 and 1:64 to 1:256, respectively. Ethanol (50% and 70%) plus 1% alpha-mangostin extract disinfectant exhibited antibacterial activity with MICs and MBCs at dilutions of 1:32-1:512 and 1:16-1:128, respectively. Moreover, isopropanol and ethanol (30%) with 1% alpha-mangostin extract disinfectant demonstrated antibacterial activity with MICs and MBCs at dilutions of 1:16-1:256 and 1:4-1:128, respectively. However, isopropanol (50% and 70%) and ethanol (50% and 70%) disinfectants showed weaker antibacterial activity than alpha-mangostin extract-containing alcohol solutions. Although isopropanol (30%) disinfectant demonstrated antibacterial activity (MICs and MBCs at dilutions of 1:16-1:32), the 30% ethanol solution did not show any activity against either bacterium. In addition, alpha-mangostin extract exhibited stronger antibacterial activity (MICs and MBCs at dilutions of 1:625-1:5,000) than all alcohol solutions. Conclusion: The combination of isopropanol and ethanol disinfectants with alpha-mangostin-rich extract exhibited significant antibacterial effectiveness against MRSA and S. pseudintermedius. The enhancement of efficacy by alpha-mangostin-rich extract suggests promising opportunities for enhancing disinfection approaches.