Ononis natrix L. (O. natrix) belongs to Fabaceae family and ?grows on the coast of Mediterranean Sea. The current study aims to investigate the antioxidant, anti-inflammatory and anti-cancer activities of the methanolic extract of O. natrix and identify the phytochemical constituents responsible for these effects. Gas chromatography-mass spectrometry (GC-MS) was employed to characterize the phytochemicals found in the extract. The human red blood cells (RBCs) membrane stabilization method, ferric reducing antioxidant power (FRAP), total antioxidant capacity (TAC), 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay and MTT viability assay were used to investigate the anti-inflammatory, antioxidant and anti-cancer activities. The results showed that methyl stearate (39.48%) and hexadecanoic acid, methyl ester (35.61%) were the most relatively abundant phytochemicals identified by GC-MS. The % hemolysis inhibition for RBC membrane achieved by O. natrix extract was 99.6 ± 1% versus that by indomethacin was 99.9 ± 0.6%. Additionally, the DPPH radical scavenging activity of O. natrix extract versus ascorbic acid was 97 ± 0.3% and 98 ± 0.2%, respectively. The O. natrix extract showed a lower anti-cancer activity against DLD-1 cells (IC50 = 57.13±4.9 µg/mL), MCF-7 cells (IC50 = 96.69±6.2 µg/mL) and A549 cells (IC50 = 126.63±10.4 µg/mL), when compared with the anti-cancer drug; Cisplatin. Therefore, O. natrix extract showed significant anti-inflammatory, antioxidant and anti-cancer properties, which could be attributed to methyl stearate and hexadecanoic acid, methyl ester constituents.