Objective <p>To investigate the association of early-life exposure to famine with the risk of mortality in later life, as well as to assess the mediating effect of BMI in adulthood on the relationship between early-life famine exposure and long-term mortality risk.</p> Methods <p>The China Health and Nutrition Survey (CHNS) served as the basis for the study’s data analysis. A total of 8,085 individuals participated in this study. All subjects were categorized into five groups: no exposure group, fetal exposure group, early childhood exposure group, mid-childhood exposure group, and late childhood exposure group. The association of famine exposure with mortality was analyzed using Cox proportional hazards regression models.</p> Results <p>Exposure to famine in mid-childhood and late childhood exposure was significantly associated with an increased mortality risk (<i>HR</i>: 2.453 and 3.016, 95%<i>CI</i>: 1.532–3.927 and 1.830–4.971, <i>P</i> &lt; 0.001 and &lt; 0.001, respectively). BMI mediated the association of famine exposure with mortality in mid-childhood (<i>P</i> = 0.004) and late childhood exposure (<i>P</i> &lt; 0.001), the mediated proportion were 15.01% for exposure in mid-childhood and 10.22% for exposure in late childhood. However, when the sample was restricted to individuals with a narrower age range for enhanced comparability, the effect of fetal exposure became statistically significant (<i>HR</i>: 2.483, <i>95% CI</i>: 1.346–4.579, <i>P</i> = 0.004).</p> Conclusion <p>Exposure to China’s Great Famine during mid- and late childhood resulted in a higher long-term mortality rate. Additionally, BMI acted as a mediator between famine exposure and the mortality. Moreover, the age-limited analysis highlighted the significant effect of fetal exposure on mortality.</p>