Liver diseases have become a leading cause of death among people with AIDS (PWA). This study aimed to investigate whether PWA experienced excess mortality related to liver diseases as compared to the general population (non-PWA), using a multiple cause of death (MCoD; i.e. all conditions reported on death certificates) approach. Methods A population-based, nationwide, retrospective cohort study was conducted among Italian people, aged 15-74 years, who had been diagnosed with AIDS since 2006. Date of death and MCoD data were retrieved, up to December 2015, by individual record linkage with national mortality data. Sex-and age-standardized mortality ratios (SMRs), with 95% confidence intervals (CIs), were estimated by dividing the observed number of deaths related to a specific condition among PWA to the expected number, based on non-PWA mortality rates. Results Among 7912 PWA (34 184 person-years), 2076 deaths occurred. The number of death certificates reporting liver diseases among MCoDs was 583 (28.1%), including 382 (18.4%) reporting viral hepatitis, 370 (17.8%) reporting nonviral liver diseases, and 41 (2.0%) reporting liver cancers. The corresponding SMRs were 40.4 (95% CI 37.2-43.8) for all liver diseases, 131.1 (95% CI 118.3-145.0) for viral hepatitis, 29.9 (95% CI 27.0-33.1) for nonviral liver diseases, and 11.2 (95% CI 8.1-15.3) for liver cancers. Particularly elevated SMRs emerged among PWA aged 15-49 years and those infected by injecting drug use. Conclusions The high excess liver-related mortality observed among PWA warrants preventive actions to limit the burden of viral hepatitis coinfections, alcohol abuse, and metabolic disorders, especially among younger PWA and injecting drug users.