Objective: the Moringa oleifera leaf (MO) has active compounds that may be beneficial for peri-implantitis therapy. This research aims to analyze the phytochemical, antioxidant, and antibacterial properties of Moringa oleifera L. nanosuspension (MON) extract in peri-implantitis-related bacteria. Methods: MON extract phytochemical analysis was conducted to examine active compounds such as flavonoids, saponins, quinones, alkaloids, tannins, terpenoids, and steroids. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay for antioxidant capacity was evaluated, and gas chromatography-mass spectrometry for the detection of volatile active compounds in MON extract was performed. Turax was used to create MON extract at concentrations of 1% and 2%, and then a particle size analysis was carried out. Prevotella intermedia (Pi), Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), and Fusobacterium nucleatum (Fn) were tested for antibacterial activity of MON extract, comparing them with doxycycline as the reference drug and using the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), and diffusion zone methods. Results: MON extract has lower antioxidant capacity than vitamin C. Flavonoids, saponins, quinones, alkaloids, tannins, terpenoids, and steroids were found in MON extract. 1% and 2% of MON extract has 10–40 d nm particle size. MIC, MBC and diffusion examination of 1% and 2% MON extract on Aa, Pg, Pi, and Fn were seen at concentrations of 25% and 12.5% with significantly different (p < 0.05) in vitro. Conclusion: MON extract has potential antioxidant activity, and 1% or 2% of MON extract has antibacterial properties toward Aa, Pg, Pi, and Fn at concentrations of 25% and 12.5%, with significant differences. © 2023