Background: Despite the benefits of breast milk and colostrum for the health and survival of children, early prelacteal feeding is commonly practiced worldwide, particularly in lowand middle-income countries. The aim of this study was to evaluate the pooled prevalence and determinants of prelacteal feeding in Eastern Africa. Methods: This study was carried out within 11 East African countries from 2010 to 2018, a pooled study of prelacteal feeding was performed. For assessing model fitness and contrast, intra-class correlation coefficient, median odds ratio, proportional change in variance, and deviance were used. In order to identify possible covariates associated with prelacteal feeding in the study area, the multilevel multivariable logistic regression model was adapted. Adjusted Odds Ratio was used with 95% confidence interval to declare major prelacteal factors. Results: The pooled prevalence of prelacteal feeding in Eastern Africa was 12% (95% CI: 11.42-12.53%), with the highest prevalence of prelacteal feeding in the Comoros (39%) and the lowest in Malawi (3%). Multilevel multivariable logistic regression model; wealth index (AOR = 1.22; 95% CI 1.03-1.34), ANC visit (AOR = 1.42; 95% CI: 1.12-1.79), institutional delivery (AOR = 0.58; 95% CI: 0.58-0.64), small birth size (AOR = 1.14; 95% CI: 1.30-1.26), delivery type (AOR = 2.61; 95% CI: 2.30-2.96), and high community ANC visit (AOR = 0.90; 95% CI: 0.84-0.97) were significantly associated with prelacteal feeding in Eastern Africa. Conclusion: In East Africa, the magnitude of prelacteal feeding was still high. The possible determinants of prelacteal feeding in Eastern Africa were wealth index, birth interval, delivery mode, place of delivery, ANC visit, and community ANC visit. Structural improvements are required for women with caesarean births to achieve optimal breastfeeding practice in Eastern Africa.