The Russia–Ukraine war, which began in 2022, has triggered unprecedented geopolitical and economic disruptions, reshaping trade, energy security, and social stability worldwide. This paper examines its impacts on Germany, representing the European Union (EU), and Nigeria, representing Sub-Saharan Africa (SSA), using the Synthetic Control Method (SCM) to construct counterfactual scenarios. Seven key indicators—GDP growth, inflation, access to clean fuels, poverty gap, food imports, cereal yield, and food production index—were analyzed for the period 2010–2023, with projections through 2030. Findings reveal sharp divergences in macroeconomic performance: Germany experienced immediate inflationary spikes and a GDP contraction by 2023, while Nigeria faced intensified inflationary pressures, declining food security, and persistent energy access challenges. Synthetic controls suggest both countries underperformed compared to their counterfactual trajectories, with Germany’s gap concentrated in industrial and energy-linked sectors, and Nigeria’s in agricultural output and poverty reduction. Projections to 2030 indicate partial recovery for both, contingent on energy diversification, social protection, and trade adaptation strategies. The study offers comparative policy lessons, emphasizing the role of structural resilience, economic diversification, and coordinated international responses in mitigating the economic costs of geopolitical conflicts.