Açaí berry is a fruit from the tree commonly known as açaízeiro ( Mart.) originated from the Amazonian region and widely consumed in Brazil. There are several reports of the anti-inflammatory activity of its pulp and few data about the seed's potential in inflammation control. This work aimed to evaluate the effect of catechin-rich açaí extract on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and carrageenan-induced paw edema. The treatment with ethyl acetate extract (EO-ACET) was used in an in vitro model performed with macrophages stimulated by LPS, in which pro-inflammatory markers were evaluated, and in an in vivo model of acute inflammation, in which edema inhibition was evaluated. EO-ACET showed an absence of endotoxins, and did not display cytotoxic effects in RAW 264.7 cells. LPS-stimulated cells treated with EO-ACET displayed low levels of nitrite and interleukins (IL's), IL-1β, IL-6 and IL-12, when compared to untreated cells. EO-ACET treatment was able to inhibit carrageenan-induced paw edema at 500 and 1000 mg/kg, in which no acute inflammatory reaction or low mast cell counts were observed by histology at the site of inoculation of λ-carrageenan. These findings provide more evidence to support further studies with seeds for the treatment of inflammation.