Background <p>Breast cancer remains a major global health concern. This study aims to assess the epidemiological trends of breast cancer, with a focus on mortality rates, primary risk factors, and their associations with age, time period, and birth cohort.</p> Methods <p>Mortality data were obtained from the Global Burden of Disease Study 2021. An age-period-cohort model was employed to analyze trends in breast cancer mortality and its primary risk factors.</p> Results <p>Globally, breast cancer outcomes remained poor between 1992 and 2021, with an estimated 660925.3 deaths in 2021. Mortality rates declined significantly in high and high-middle socio-demographic index (SDI) countries [-1.56%, 95% CI (-1.7 to -1.43)], [-1.03% (-1.11 to -0.94), respectively], but increases markedly in low-middle SDI countries [1.18% (1.13 to 1.23)], with little change in other regions. A global shift in breast cancer-related deaths from younger to older age groups was observed, and mortality increased sharply with advancing age. Positive period and cohort effects were primarily seen in high and high-middle SDI countries, whereas adverse effects were more common in lower-SDI regions. Diets high in red meat emerged as the leading risk factor for breast cancer mortality worldwide, although favorable trends were noted in high and high-middle SDI countries.</p> Conclusions <p>Despite a global decline in breast cancer mortality, many countries continue to experience unfavorable period and cohort effects. A notable rise in mortality among individuals aged 80 and older was observed across all SDI quintiles, underscoring the urgent need to strengthen healthcare systems for aging breast cancer populations worldwide.</p>