The genus Pyrus, which includes pear species, comprises approximately 22 species and 5,000 subspecies. Pears are commercially important due to their environmental adaptability and are widely distributed across North Africa, Europe, and Asia. Pyrus species are rich in phytochemicals known for their anticancer, antiviral, and antioxidant properties. This study investigates the chemical composition and biological activity of leaf, stem, and fruit extracts of Pyrus calleryana growing in Egypt, using UPLC-MS/MS and GNPS molecular networking, and assessing antioxidant and enzyme inhibitory activities. A total of 73 compounds were identified, the majority of which were phenolic compounds. These included benzoic and cinnamic acid derivatives, flavonoids, triterpenoids, fatty acids, phospholipids, glycolipids and sugars. The stem extract exhibited significant in vitro antioxidant and enzyme inhibitory activity. Antioxidant activity of stems extract was assessed (in comparison to other organs) in several antioxidant assays, e.g. DPPH (367.06 ± 4.65 mg TE/g), ABTS (392.8 ± 7.04 mg TE/g), FRAP (206.73 ± 5.12 mg TE/g), phosphomolybdenum (1.89 ± 0.05 mmol TE/g), and others. Furthermore, the P. calleryana leaf extract inhibited MDA-MB-231 cell viability in a concentration-dependent manner after 48 h. These results highlight the promising potential of Pyrus calleryana as a rich source of bioactive compounds with antioxidant, enzyme inhibitory, and cytotoxic activities, supporting its further exploration in pharmaceutical and nutraceutical applications. Keywords: Antioxidant, Cell cycle analysis, Pyrus calleryana, Rosaceae, UPLC-MS/MS