Aquaculture is promoted as a sustainable pathway to enhance food security and coastal livelihoods in developing nations. However, its integration into national policy frameworks and its tangible impacts on local communities in the Horn of Africa remain critically under-examined. This study analyses the policy and governance structures shaping aquaculture development and evaluates its contribution to household food security and income diversification in coastal communities. A mixed-methods approach was employed, combining a systematic policy document review with a household survey (n=217) across three coastal sub-regions. The relationship between policy awareness, engagement in aquaculture, and food security was modelled using a logistic regression: $\logit(p_i) = \beta_0 + \beta_1 X_{1i} + \beta_2 X_{2i} + \epsilon_i$, where $p_i$ is the probability of improved dietary diversity. Robust standard errors were clustered at the community level. Policy frameworks were found to be fragmented, with weak institutional coordination hindering implementation. Households engaged in aquaculture activities reported a 32% higher dietary diversity score (95% CI: 24% to 40%) than non-engaged households. A key theme was the critical role of women's access to microcredit in sustaining small-scale operations. While aquaculture demonstrates significant potential for improving food security, its benefits are constrained by disjointed governance and unequal access to capital and training. Integrate aquaculture policy within a cohesive national food security strategy; strengthen extension services targeting women's groups; and establish community-based monitoring of coastal resource use. aquaculture policy, food security, coastal livelihoods, governance, Horn of Africa This paper provides the first integrated analysis of national aquaculture policy and household-level survey data from the country, identifying a specific mechanism linking microcredit access for women to project sustainability.