The study analyzed the epidemiologic trends of liver cancer in adolescents and young adults (AYA, 15–39 years) from 1990 to 2021 based on Global Burden of Disease 2021 data. From 1990 to 2021, the absolute number of cases and deaths increased, but the age-standardized incidence rate (ASIR) peaked in the early 2000s and declined to 0.82 per 100,000 in 2021, with the age-standardized mortality rate (ASMR) falling to 0.65 per 100,000. The steepest decline in ASIR occurred in 2001–2005. Men had more than twice the incidence of women (ASIR 1.22 vs. 0.42). East Asian and West African regions such as Mongolia and The Gambia had the highest burden, while countries with a medium sociodemographic index (SDI) carried the highest absolute number of cases. Projections predict an increase in absolute cases to 45,352 and deaths to 31,448 by 2030, despite falling age-standardized rates and narrowing health inequalities. The authors emphasize the need for targeted global measures for prevention and control.