This investigation aimed to assess the antioxidant, antimicrobial, and anticancer activity of Persea americana leaves extracts (ethanol, ethyl acetate, and petroleum ether). The total phenolic and flavonoid contents were measured, while the different phenolic compounds were recognized using the HPLC instrument. Antioxidant activity was measured using not only DPPH but also ABTS. In addition, antimicrobial activity was estimated via the agar well diffusion method against microbial strains (Bacillus Subtilis, Aspergillus fumigatus, Candida albicans, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli). Anticancer activity was determined against the human lung normal fibroblast (WI 38) and human lung carcinoma (A 549) in addition to human liver carcinoma (HepG2) cell lines by the MTT protocol. The results showed that the highest total phenolic and flavonoid content was found in the ethanolic extract, with 217.58 ± 1.52 mg GAE/g and 71.55 ± 1.57 mg QE/g, respectively, compared with other extracts. The ethanolic extract contains very high concentrations of chlorogenic acid, naringenin, rutin, ferulic acid, syringic acid, gallic acid, coumaric acid, caffeic acid, methyl gallate, vanillin, and ellagic acid. The ethanolic extract gave the highest antioxidant activity using DPPH and ABTS (IC50 = 14.33 and 16.03 μg/ml, respectively). It also has the highest antimicrobial activity against the different microorganisms examined. The ethyl acetate extract has the highest anticancer activity against A 549, HepG2 and WI 38 cell lines (IC50 = 44.28, 88.91 and 90.52 μg/ml, respectively). P. americana leaves extracts have strong antioxidant ability, strong antimicrobial activity, and very good cytotoxic activity.