Resistant starch (RS) is a non-digestible fraction of dietary starch that modulates glucose and lipid metabolism. In this study, a RS-enriched high-amylose rice (R-HAR) was developed using a mild citric acid-assisted thermal process to enhance RS content and evaluated for its potential to alleviate high-fat diet (HFD)-induced metabolic disorders in mice. The RS content of the diet increased proportionally with the inclusion of R-HAR. Long-term R-HAR supplementation significantly reduced body weight gain and adiposity compared with the HFD control. Serum biochemical analyses revealed that R-HAR improved dyslipidemia by lowering total cholesterol, LDL-cholesterol, ALT, and AST levels while elevating adiponectin concentration. Moreover, R-HAR administration markedly ameliorated fasting blood glucose, fasting insulin, and HOMA-IR values, indicating restored insulin sensitivity. Histological evaluation further confirmed that R-HAR reduced hepatic steatosis and adipocyte hypertrophy in a dose-dependent manner. These beneficial effects were more pronounced than those observed with untreated high-amylose rice (HAR), suggesting that the increase in RS fraction achieved through organic acid treatment contributed to improved metabolic balance. Overall, these findings demonstrate that R-HAR, as a food-based functional carbohydrate, effectively ameliorates HFD-induced glucolipid dysregulation and may serve as a practical dietary strategy to prevent obesity-related metabolic complications.