Objective Chronic hepatitis B (CHB) and metabolic dysfunction-associated fatty liver disease (MAFLD) are the leading causes of hepatocellular carcinoma (HCC). We aim to explore the impact of concurrent MAFLD on the risk of HCC in CHB. Methods Patients with CHB were consecutively recruited from 2006 to 2021. MAFLD was defined by steatosis and either obesity, diabetes mellitus, or other metabolic abnormalities. The cumulative incidence of HCC and associated factors were compared between the MAFLD and non-MAFLD groups. Results 10,546 treatment-naïve CHB patients were included with a median follow-up of 5.1 years. CHB patients with MAFLD ( n  = 2212) had fewer hepatitis B e antigen (HBeAg)-positivity, lower HBV DNA levels, and Fibrosis-4 index compared with the non-MAFLD group ( n  = 8334). MAFLD was independently associated with a 58% reduced risk of HCC (adjusted hazard ratio aHR 0.42, 95% confidence interval CI 0.25–0.68, p  < 0.001). Furthermore, steatosis and metabolic dysfunction had distinct effects on HCC. Steatosis was protective against HCC (aHR 0.45, 95% CI 0.30–0.67, p  < 0.001), while a greater burden of metabolic dysfunction increased the risk (aHR 1.40 per dysfunction increase, 95% CI 1.19–1.66, p  < 0.001). The protective effect of MAFLD was further confirmed in analysis with inverse probability of treatment weighting (IPTW), patients who had undergone antiviral therapy, those with probable MAFLD, and after multiple imputation for missing data. Conclusions Concurrent hepatic steatosis is independently associated with a lower risk of HCC, whereas the increasing burden of metabolic dysfunction aggravates the risk of HCC in untreated CHB patients.