Context: Treatment for osteoarthritis focuses on controlling pain, lowering inflammation, delaying cartilage deterioration, and minimizing impairment. Aims: To evaluate the bioactivity of leaf extract 'markisa' (Passiflora edulis, MLE) as an in vitro radical scavenger, and an in vivo edema reducer and pro-inflammatory mediators in an osteoarthritis rat model. Methods: MLE was prepared by an ultrasonication method with ethanol. First, the in vitro antioxidant activity of MLE was assessed with ABTS reagent, and the total phenolics (TPC) and flavonoid (TFC) contents were determined. Furthermore, in vivo tests were conducted. Wistar rats were induced osteoarthritis by intraarticular injections of sodium iodoacetate (13.5 mg/kg BW) and observed for one month. MLE was administered orally to animal models in doses of 100, 200, and 400 mg/kg BW every day for two weeks. Body weight and knee edema enlargement were observed every week. At week 6th, all animals were sacrificed for evaluation of spleen weight, hematology analysis (leukocyte and lymphocyte number), and pro-inflammatory mediators assay (NO, IL-6, TNF-α, and MMP-9). Results: This study showed that MLE has antioxidant capacity 13.26 ± 0.7 mol TE/g, TPC 8.17 ± 0.03 mg GAE/g, and TFC 3.28 ± 0.3 mg QE/g. In vivo tests showed that MLE-treated rats had reduced knee edema, hematological improvement (decreased NO, IL-6, and TNF-α), spleen enlargement, and protection against cartilage degradation by decreasing MMP-9. Conclusions: These findings suggest that MLE therapy has the potential to restore the state of osteoarthritic rats to normal, with varying degrees of dose-dependent improvement.