Background: Plant-derived antioxidants have been products of choice in therapeutic formulations for their potent free radical scavenging activity and mitigating and curing illnesses and diseases associated with oxidative stress. Capparis L. includes species with unprecedented nutritional and medicinal values, and hence offers a diverse pool of phytochemicals implicated in antioxidant activity. Objective: The current study was designed to assess the chemical variation, total phenols content (TPC), total flavonoids content (TFC), in vitro and in vivo antioxidant activities of different extracts obtained from Capparis cartilaginea and Capparis ovata from Jordan. Materials and Methods: The ethanolic extract from each species was partitioned in different solvents and the TPC, TFC, and antioxidant activity for each extract was examined. The in vitro antioxidant activities were tested by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino–bis (3-ethylbenzoline-6-sulfonic acid diammonium salt (ABTS) radical scavenging methods in addition to the metal ion chelating effect (MCE) and hydroxyl radical assay methods. The butanol extract was investigated for its in vivo effect on the activities of serum superoxide dismutase (SOD) and glutathione peroxidase (GPX) in mice (100 mg/kg, intraperitoneally for 12 days). Results: The butanol fraction of both plants had a dose-dependent in vitro antioxidant activity. The treatment of mice with the butanol extract of both species for 12 days significantly increased the activities of serum SOD and GPX. Principal component analysis indicated that DPPH, TFC, hydroxyl radical had major variability in the antioxidant activities of the two investigated Capparis species. Results of this study underscores enrichment of the two studied Capparis species with phenolics and flavonoids that could account for much of their antioxidant activities.