In 1991, a mass immunization campaign against the hepatitis B virus (HBV) for children and teenagers was introduced in Italy. This study evaluated the impact of the immunization campaign on the incidence and modes of HBV transmission. Acute HBV cases of viral hepatitis were reported to the National Surveillance System (SEIEVA). Hepatitis A cases reported to the same system were used as controls to calculate the adjusted odds ratios and the population attributable risk for potential risk factors. The incidence of acute HBV declined from 5.0 in 1990 to 0.4 in 2019 per 100,000 population. The fall was almost total in people targeted by the campaign: in 2019, zero cases (100% reduction) in the age-group 0-14 years and 0.1 cases per 100,000 population (99.4% reduction) in the age-group 15-24 years were reported. In the decade 2010-2019, nearly one-fifth (19.3%) of cases occurred in foreigners. Intravenous drug use is no longer a risk factor (OR = 0.7; 95% CI = 0.5-1.02). Beauty treatments, risky sexual exposure, and household contact with an HBsAg carrier were found to be independent predictors of acute hepatitis B. The HB vaccination campaign proved effective in minimising acute HBV in Italy. Control of the infection is close to being reached for the first time in Europe.