Although acute hepatitis B virus (HBV) infections in Europe have declined, thousands of chronic cases are still identified annually, placing a strain on healthcare systems. This study aimed to retrospectively analyse the patient profile, hospitalisation course, and admission causes for HBV infection in Poland in 2012–2023. The first-time HBV hospital admissions in Poland (ICD-10 codes B16; B18.0–B18.1) between 2012 and 2023 (n = 29,435) were analysed, examining trends by gender, age, residence and admission mode. The HBV first-time hospitalisation rate fell over tenfold, from 17.59 per 100,000 population in 2012 to 1.67 in 2021, rising to 3.45 in 2023. During 2020–2022, the share of hospitalisations with acute HBV increased (9.3% vs. 3.8% pre-pandemic; p < 0.05), but their rate was twofold lower (0.18 vs. 0.32 per 100,000 population). The mean patient age rose from 40.9 in 2012 to 51.5 years in 2023 (p < 0.05). Men from urban areas accounted for most hospitalisations, were older than rural patients, and had the highest emergency admission rates. Women from rural areas had the lowest hospitalisation share, were younger, and had over three times fewer emergency admissions. From 2012 to 2023, Poland experienced a major decline, then a resurgence, in HBV hospitalisations, with a higher share of acute cases during the COVID-19 pandemic. Hospitalised patients aged significantly, with urban men most affected. These patterns underscore the need for targeted HBV prevention and management strategies for aging urban populations.