To evaluate the cost-effectiveness of risk-stratified hepatocellular carcinoma (HCC) screening in diabetic patients with metabolic dysfunction-associated steatotic liver disease (MASLD). A state-transition model from a healthcare payer perspective on a lifetime horizon. Japan. A hypothetical cohort of 50-year-old diabetic patients with MASLD risk-stratified according to degree of obesity and progression to cirrhosis. Metabolic dysfunction-associated steatotic liver (MASL), metabolic dysfunction-associated steatohepatitis (MASH) and MASH cirrhosis are progressive manifestations of this specific type of liver disease. Abdominal ultrasound (US), US with alpha-fetoprotein (AFP), US with AFP and lectin-reactive alpha-fetoprotein (AFP-L3), CT, extracellular contrast-media-enhanced MRI (ECCM-MRI), gadoxetic acid-enhanced MRI (EOB-MRI) and no screening. Costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs), early-stage HCC cases, advanced-stage HCC cases and HCC-related deaths. EOB-MRI is the most cost-effective screening method for non-obese diabetic patients with MASH cirrhosis and for obese diabetic patients with MASH and MASH cirrhosis. Cost-effectiveness was sensitive to HCC incidence in non-obese diabetic patients with MASH cirrhosis and obese diabetic patients with MASH, and the adherence rate of HCC screening in obese diabetic patients with MASH. When the semiannual HCC incidence was between 0.008 and 0.0138 in non-obese diabetic patients with MASH cirrhosis, US with AFP was more cost-effective than EOB-MRI. Cost-effectiveness acceptability curves showed that EOB-MRI was 50.7%, 96.0% and 99.9% cost-effective in obese diabetic patients with MASH and non-obese diabetic patients with MASH cirrhosis, and obese diabetic patients with MASH cirrhosis at a willingness-to-pay level of $50 000 per QALY gained. Compared with no screening in 100 000 non-obese diabetic patients with MASH cirrhosis and obese diabetic patients with MASH cirrhosis, EOB-MRI reduced total costs by US$69 million and by US$142 million, increased lifetime effectiveness by 12 546 QALYs and by 15 815 QALYs, detected 17 873 and 21 014 early-stage HCC cases, and averted 2068 and 2471 HCC-related deaths, respectively. Of all HCC screening methods for diabetic patients with MASH cirrhosis, EOB-MRI yields the greatest cost-saving with the highest QALYs, detects the greatest number of early-stage HCC cases and averts the greatest number of advanced-stage HCC cases and HCC-related deaths. The findings provide important insights for the precise implementation of risk-stratified HCC surveillance to reduce morbidity and mortality and improve the quality of life in diabetic patients with MASLD.