Ziziphus spina-christi, a medicinal plant widely used in traditional medicine, is known for its rich phytochemical composition and diverse therapeutic properties. This study investigates the phytochemical profile, antioxidant activity, and cytotoxic effects of the aqueous extract of Z. spina-christi. Phytochemical analysis revealed high concentrations of phenolics (105.48±0.42 GAE/g), tannins (99.02±0.45 GAE/g), flavonoids (32.39±0.15 QE/g), and flavonols (24.10±0.21 QE/g), indicative of its bioactive potential. Antioxidant assays demonstrated significant free radical scavenging activity, with IC₅₀ values of 15.11±2.31 μg/mL (DPPH) and 18.30±0.11 μg/mL (ABTS). Cytotoxicity testing against Caco-2 cells showed moderate inhibitory effects with an IC₅₀ of 209.245±8.32 μg/mL, suggesting potential anticancer activity. UV-vis and zeta potential analyses supported the stability and presence of phenolic compounds, while the IR spectrum highlighted hydroxyl and carbonyl functional groups. A comparative discussion with previous studies revealed variations in bioactivities based on dosage, duration, and extraction methods, emphasizing the dual nature of the plant as both a therapeutic agent and a potential toxicant at higher doses. These findings reinforce the promise of Z. spina-christi as a source of natural antioxidants and cytotoxic agents while underscoring the need for rigorous safety assessments for its clinical use.