SummaryBackgroundThe prevalence of at‐risk metabolic dysfunction‐associated steatohepatitis (at‐risk MASH) has not been systematically assessed.AimTo delineate the prevalence of at‐risk MASH in a large population‐based cohort.MethodsWe conducted a cross‐sectional analysis of 40,189 patients in the UK Biobank who underwent liver MRI. Hepatic steatosis was determined by proton density fat fraction (PDFF) ≥5%. Based on AASLD criteria, participants were classified as alcohol‐associated steatotic liver disease (ALD), metabolic dysfunction‐associated steatotic liver disease (MASLD), combined metabolic alcoholic liver disease (MetALD) and at‐risk MASH.ResultsAmong 40,189 patients, 10,886 (27.0%) had a PDFF ≥5%, indicating SLD. Among patients with SLD, 1% had ALD, 89.0% had MASLD, 7.9% had MetALD and 2.2% had at‐risk MASH. The at‐risk MASH group, which included 0.6% of the general population, had the highest mean liver fat on MRI and the highest BMI. Serum biomarkers highlighted increased inflammation and metabolic changes in at‐risk MASH. The prevalence of MASLD was significantly higher among men with a BMI ≥30 kg/m². Non‐obese women showed only a 12% risk of MASLD. Conversely, MetALD had similar prevalence in obese men and women and was absent in non‐obese women.ConclusionsMASLD is prevalent among patients with elevated PDFF on MRI. There are different sex‐ and BMI‐specific prevalence of different steatotic liver disorders. At‐risk MASH demonstrates the most severe metabolic and inflammatory profiles. This study provides novel estimates for the at‐risk MASH population that will be eligible for treatment with pharmacologic therapy when approved by regulatory authorities.