Gynura segetum, family Compositae, is a cultivated species and can be found growing in the tropical regions of Indonesia and Malaysia. The plant is known for its use for the treatment of cancer, inflammation, diabetes, hypertension and skin afflictions. In the current study, in vivo anti-inflammatory effect of the methanol extract G. segetum leaf and its antioxidant effect in vitro have been investigated for the first time. The in vitro antioxidant activities of the methanol extract were measured using common methods including total phenolic content; total flavonoid content; scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and β-carotene bleaching assays. The in vivo anti-inflammatory activities were tested using the cotton pellet implanted animal model. The measurement of pro-inflammatory cytokine (TNF-α and IL-1) levels in the blood samples of the rats was carried out by using ELISA kits. The inhibitory activity on cyclooxygenase (COX) enzyme of methanol extract was also evaluated. The methanol extract exhibited good antioxidant activity which is associated with their total phenolic and flavonoid contents. Methanol extract strongly inhibited the granuloma tissue formation in rats and the anti-inflammatory potential was mediated through the inhibition of pro-inflammatory cytokines and COX-2 enzyme activities. Taken together, the present study suggests that G. segetum's leaf is a natural source of antioxidants and has potential therapeutic benefits against chronic inflammation.