(1) Background: Infant mortality is viewed as a core health indicator of overall community health. Although globally child survival has improved significantly over the years, Sub-Saharan Africa is still the region with the highest infant mortality in the world. In Ethiopia, infant mortality is still high, albeit substantial progress has been made in the last few decades. However, there is significant inequalities in infant mortalities in Ethiopia. Understanding the main sources of inequalities in infant mortalities would help identify disadvantaged groups, and develop equity-directed policies. Thus, the purpose of the study was to provide a diagnosis of inequalities of infant mortalities in Ethiopia from four dimensions of inequalities (sex, residence type, mother’s education, and household wealth). (2) Methods: Data disaggregated by infant mortalities and infant mortality inequality dimensions (sex, residence type, mother’s education, and household wealth) from the WHO Health Equity Monitor Database were used. Data were based on Ethiopia’s Demographic and Health Surveys (EDHS) of 2000 (n= 14,072), 2005 (n= 14,500), 2011 (n= 17,817), and 2016 (n= 16,650) households. We used the WHO Health Equity Assessment Toolkit (HEAT) software to find estimates of infant mortalities along with inequality measures. (3) Results: Inequalities related to sex, residence type, mother’s education, and household wealth still exist; however, differences in infant mortalities arising from residence type, mother’s education, and household wealth were narrowing with the exception of sex-related inequality where male infants were markedly at a disadvantage. (4) Conclusions: Although inequalities of infant mortalities related to social groups still exist, there is a substantial sex related infant mortality inequality with disproportional deaths of male infants. Efforts directed at reducing infant mortality in Ethiopia should focus on improving the survival of male infants.