Rationale and Background: : Guava leaf (Psidium guajava L.) extracts are widely used in traditional medicine and pharmaceutical industries. The antioxidant compounds in P. guajava leaves are known to have various beneficial effects including anti-inflammatory, anti-hyperglycemic, hepatoprotective, analgesic, and anti-cancer effects, as well as protection against cardiovascular diseases. This study analyzed the functional groups, phenolic compounds, and in-vitro antioxidant capacity of ethanol-extracted Psidium guajava leaves. Additionally, formulations of herbal toothpaste were developed and subsequently evaluated for their physicochemical and antibacterial properties. Methodology: : Psidium guajava leaves were extracted using two differential techniques to determine the most effective extraction method. Phytochemical screening and biological activity tests were then conducted. Finally, herbal toothpaste was formulated, and its physicochemical properties, including antibacterial activity, were evaluated. Results: : Phytochemical analysis confirmed the presence of flavonoids, tannins, terpenoids, and alkaloids in both ultrasonic and reflux extractions. Total phenolic compound analysis showed that ultrasonic extraction yielded a higher value (213.11 ± 2.93 mg GAE/g dw) than reflux extraction (69.75 ± 4.64 mg GAE/g dw). The DPPH assay also indicated a higher antioxidant capacity for ultrasonic extraction (1146.92 ± 21.85 µM TE/g dw) compared to reflux extraction (606.19 ± 13.93 µM TE/g dw). The ABTS assay was similar for both extraction methods, whereas the FRAP assay showed higher values for ultrasonic extraction (378.44 ±19) than reflux extraction (213.11 ± 2.93). Additionally, ultrasonic extraction exhibited better antibacterial activity against S. aureus than the reflux method. The stability evaluation showed favorable results for color, appearance, texture, smell, taste, foaming, and pH. Conclusion: This study demonstrated that Psidium guajava L. extracts possess high total phenolic content and strong antioxidant activity. The formulated herbal toothpaste exhibited a promising antibacterial profile, supporting the traditional use of P. guajava in medicine and its potential for development into various pharmaceutical and industrial products in the future.