In the present study, the brown seaweed Spatoglossum schroederi was submitted to extraction procedures in order to obtain methanol (MET) extract and its hexane (HEX) and chloroform (CLR) fractions. All samples were evaluated for total phenolic and flavonoid contents as well as antioxidant and anti-inflammatory properties. The HEX fraction was the richest in total phenolic content, while CLR in total flavonoid content. MET, HEX, and CLR exhibited potent dose-dependent antioxidant activity by the total antioxidant capacity (TOAC) and reducing power methods and linear regression evidenced that the antioxidant activity of S. schroederi is due mainly to the flavonoid content. Following, MET extract and its fractions were evaluated for anti-inflammatory activity. Algae samples inhibited significantly the paw edema induced by carrageenan or dextran, myeloperoxidase activity, neutrophil migration induced by carrageenan, IL-1β concentration, and increase on IL-10 level in the peritoneal fluid of animals. Our results suggest that anti-oxidative and anti-inflammatory present in the brown seaweed S. schroederi may be related to the presence of flavonoids.