Insulin resistance (IR) is characterized by a reduced responsiveness of insulin-sensitive tissues to endogenous insulin. Excessive caloric intake promotes the accumulation of free fatty acids in skeletal muscle and the liver, resulting in the formation of lipotoxic metabolites that impair insulin signaling and glucose uptake. Although Coleus scutellarioides has demonstrated antihyperglycemic activity, its potential to ameliorate obesity-associated metabolic disturbances, particularly high-fat diet-induced insulin resistance, remains largely unexplored. IR is also associated with visceral fat accumulation, which is strongly correlated with increased body weight. Flavonoids such as quercetin have been reported to ameliorate IR in high-fat diet-fed mice. This study aimed to evaluate the effects of ethanolic extract of C. scutellarioides on body weight gain, abdominal circumference, and liver index in high-fat diet-induced mice. Twenty-five male Swiss Webster mice were randomly divided into five groups (n = 5/group), including normal control, negative control, metformin-treated, EECS 250 mg/kg, and EECS 500 mg/kg. Data were analyzed using one-way ANOVA followed by the LSD post hoc test. EECS at doses of 250 mg/kg and 500 mg/kg significantly attenuated body weight gain by 15.06% and 13.34%, respectively, while also reducing abdominal circumference and liver index compared with the negative control group (p < 0.05). These findings suggest that EECS possesses anti-obesity activity and may ameliorate metabolic alterations associated with high-fat diet feeding.