The present investigation aimed to evaluate the antioxidant activity of various extracts (water, ethanol, and essential oil extracts) from orange and lemon peels, and to determine which was the most promising one using three different antioxidant assays. Gas chromatography–mass spectrometry (GC-MS) analysis was used to determine the active ingredients of the most promising extract. In addition, the present work deals with the antimicrobial activity of the most promising extract against five different strains of pathogenic bacteria (Escherichia coli, Salmonella sp, Bacillus cereus, Staphylococcus aureus and E. coli O157 wild type strain) and its anticancer activity of against human liver cancer cells (HepG2) using cytotoxicity assay. The tested extracts from lemon and orange (peels and residues) recorded high antioxidant activity against both radical and non-radical methods. The GC/MS analysis of most promising extract (lemon peels essential oils) showed a highly complex chemical profile, containing approximately 15 different components. The identified major compound was D-Limonene and 2,6,6-Trimethyl bicyclo(3,1,1) hept-2-ene. Also, the obtained data reported that the lemon essential oil extract showed the highest antimicrobial activity against five different strains of pathogenic bacteria followed by the lemon ethanol extract against three strains of bacteria. Furthermore, the anticancer activity results revealed that the lemon essential oil extract has a very high cytotoxicity against human liver cancer cells at different tested concentrations. Conclusively, the antibacterial and cytotoxicity efficiencies were shown to be concentration dependent of the essential oil contents.