ImportanceCancer is the leading cause of death among Asian American individuals and the second leading cause of death among Native Hawaiian and Pacific Islander people.ObjectiveTo evaluate longitudinal cancer mortality trends from 1999 to 2020 among Asian American and Pacific Islander populations in the US by demographic characteristics.Design, Setting, and ParticipantsThis cross-sectional study used the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database to obtain age-adjusted cancer death rates among Asian American and Pacific Islander individuals of all ages between January 1, 1999, and December 31, 2020. Data were analyzed from January 12 to March 19, 2024.ExposuresAge, sex, cancer type, and US census regions.Main Outcomes and MeasuresTrends and average annual percent changes (AAPCs) in age-adjusted cancer-specific mortality (CSM) rates for non-Hispanic Asian American and Pacific Islander populations were estimated by cancer type, age, sex, and region using Joinpoint regression.ResultsBetween 1999 and 2020, 305 386 Asian American and Pacific Islander individuals (median [IQR] age, 69.5 [58.5-79.2] years; 51.1% male) died of cancer in the US. Overall, the CSM rate decreased by 1.5% annually. Men experienced a greater CSM rate decrease (AAPC, −1.8%; 95% CI, −2.2% to −1.3%) compared with women (AAPC, −1.1%; 95% CI: −1.2% to −1.0%). For women, death rates decreased for most cancer types but increased for uterine (AAPC, 2.5%; 95% CI, 2.0%-3.0%) and brain and central nervous system (AAPC, 1.4%; 95% CI: 0.7%-2.1%) cancers. Colorectal cancer mortality rates increased among men aged 45 to 54 years (AAPC, 1.3%; 95% CI, 0.5%-2.1%). Liver and intrahepatic bile duct cancer mortality increased for both men and women in all US census regions, uterine cancer mortality increased in all regions for women, and pancreatic cancer mortality increased in the Midwest for both men and women.Conclusions and RelevanceAlthough these findings show an overall decrease in CSM among Asian American and Pacific Islander populations, specific cancer types exhibited increased mortality rates, with further disparities by sex and age. Targeted, culturally adapted clinical and public health interventions are needed to narrow disparities in cancer mortality.