Here we investigated the anti-inflammatory effect of a blueberry extract in the carrageenan-induced paw edema model and collagen-induced arthritis model, both in rats. Along with the chemical characterization of the phenolic content of the fruits and extract, the antioxidant potential of the extract, the cellular antioxidant activity and the effects over neutrophils’ oxidative burst, were studied in order to provide a mechanistic insight for the anti-inflammatory effects observed. The extract significantly inhibited paw edema formation in an acute model the rat. Our results also demonstrate that the standardized extract had pharmacological activity when administered orally in the collagen-induced arthritis model in the rat and was able to significantly reduce the development of clinical signs of arthritis and the degree of bone resorption, soft tissue swelling and osteophyte formation, consequently improving articular function in treated animals.