Background <p>Diarrheal disease remains a leading cause of under-five mortality in East Africa. However, comprehensive contemporary comparative analyses across countries remain limited. This study quantifies the disease burden and temporal trends using the Global Burden of Disease (GBD) 2023 estimates.</p> Methods <p>We extracted the incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) for diarrheal diseases among children under five across 12 East African countries (2000–2023) from the GBD Results Tool. We analyzed the temporal trends, country-level variations, and DALYs attributable to water, sanitation, and hygiene (WASH) risk factors using descriptive analysis and trend visualization.</p> Results <p>Mortality declined by 60–87% in high-performing countries (Tanzania, 84%; Rwanda, 88%; Uganda, 82%; Ethiopia, 86%), whereas Somalia, South Sudan, and Madagascar demonstrated minimal improvement (14.7–69.2% decline), representing a 12-fold difference in 2023 mortality rates (Tanzania 36 vs. South Sudan 443 per 100,000). Corresponding DALY reductions ranged from 80 to 87% in improving countries to 15–69% in countries with stalled progress. Age-stratified analysis revealed that neonates experienced minimal decline (15%) compared with older children (60–80%). Males sustained 25–36% higher mortality and DALYs despite convergent incidence and prevalence. The WASH-attributable DALYs ranged from 3,057 per 100,000 (Tanzania) to 37,608 per 100,000 (South Sudan), with unsafe water contributing 70–80% of the burden.</p> Conclusions <p>East Africa achieved substantial but profoundly inequitable reduction in diarrheal disease mortality. Achieving SDG 3.2 requires equitable WASH investment, health system strengthening in conflict-affected regions, and integrated multisectoral approaches addressing water access, sanitation, nutrition, and healthcare delivery simultaneously.</p> Clinical trial number <p>Not applicable.</p>