Objective: While alcohol-related harm is a recognized public health priority, the capacity to address and mitigate its harm is lacking, primarily in low-income countries. Recent developments including new tools that can assess readiness for preventing alcohol-related harm, specifically in low-resource settings, can be used to determine strengths and opportunities for supporting, planning, and resource allocation. In this study, we determined the perceptions of readiness and capacity for the prevention of alcohol-related harm across East Africa among stakeholders engaged in such work. Methods: We conducted a cross-sectional survey in 2020, distributed by the East Africa Alcohol Policy Alliance to their member alliances and stakeholders across five countries in East Africa (i.e., Burundi, Kenya, Rwanda, Tanzania, and Uganda). The survey included modified measures from the Readiness Assessment for the Prevention of Child Maltreatment (RAP-CM) short form, organizational size and funding, research capacity and priorities, and perceptions related to alcohol prevention and harm both locally and in the region. Analyses were computed based on 142 persons/organizations completing the survey. Results: In terms of general readiness, the overall adjusted aggregate score for East Africa was 39.70% (ranging from 30.5% in Burundi to 47.0% in Kenya). Of the 10 domains assessed (on a 0–10 scale), across all countries, knowledge of alcohol prevention (8.43), institutional links and resources (6.15) and legislation, mandates and policies (5.46) received the highest scores. In contrast, measures pertaining to resources (i.e., material, human, technical, and informal) received the lowest score. Conclusions: Our results demonstrate substantial variability in the readiness to address alcohol-related harm across East Africa. The highest capacity was noted for knowledge towards alcohol prevention, institutional links, and legislative mandates and policies. However, important gaps were noted in terms of attitudes towards alcohol prevention, the will to address the problem, as well as material, human, and informal resources, which need to be urgently addressed to strengthen capacity for addressing and mitigating the significant toll of alcohol-related harm in the region.