The present study investigated the anti‑obesity effects of enzyme‑treated Ecklonia cava extract (EEc) in C57BL/6N mice with high‑fat diet (HFD)‑induced obesity. The EEc was separated and purified with the digestive enzymes pectinase (Rapidase X‑Press L) and cellulase (Rohament CL) and its effects on the progression of HFD‑induced obesity were examined over 10 weeks. The mice were divided into 6 groups (n=10/group) as follows: Normal diet group, HFD group, mice fed a HFD with 25 mg/kg/day Garcinia cambogia extract and mice fed a HFD with 5, 25 or 150 mg/kg/day EEc (EHD groups). Changes in body weight, fat, serum lipid levels and lipogenic enzyme levels were determined. The body weight and liver weight were increased in the HFD group compared with those in the ND group, which was significantly reduced by EEc supplementation. In addition, significant reductions in epididymal, perirenal and mesenteric white adipose tissues were present in the EHD groups and all three EHD groups exhibited decreases in insulin, leptin and glutamate pyruvate transaminase levels compared with those in the HFD group. In addition, EEc treatment significantly decreased the serum and hepatic triglyceride levels compared with those in the HFD group. However, the levels of high‑density lipoprotein cholesterol/total cholesterol ration increased significantly in EHD‑25 and ‑150 groups compared with those in the HFD group. Changes in adipogenic and lipogenic protein expression in the liver was assessed by western blot analysis. The EHD‑25 and -150 groups exhibited reduced levels of CCAAT/enhancer‑binding protein α and peroxisome proliferator activated receptor γ. However, the phosphorylation ratios of AMP‑activated protein kinase and acetyl‑CoA carboxylase were significantly increased in the liver tissue obtained from the EHD (5, ‑25 and ‑150 mg/kg/day) groups compared with those in the HFD group. EEc supplementation reduced levels of sterol regulatory element‑binding protein‑1c, adipose fatty acid‑binding protein, fatty acid synthase and leptin, while it significantly increased glucose transporter type 4 and adiponectin protein levels in the liver tissues of all three EHD groups compared with those in the HFD group. Taken together, these results suggest that EEc exerts anti‑obesity effects by reducing body weight and the serum and hepatic levels of obesity‑associated factors. Thus, EEc supplementation reduces HFD‑induced obesity in C57BL/6N mice and has the potential to prevent obesity and subsequent metabolic disorders.