The U.S.–Israel war against Iran that commenced on 28 February 2026 (Operation Epic Fury) represents the world's largest energy security crisis since the 1970s oil embargo. This paper conducts a rigorous empirical and analytical analysis of the economic impacts of the 2026 Iran–Israel-US conflict, channelled through the main identifying and contextual pathways, namely: energy markets disruption; inflation pass-through and GDP growth revision; disruption of trade and shipping; volatile financial markets and financial contagion; and asymmetric regional impacts. The paper uses Ordinary Least Squares (OLS) regression, scenario analysis, and comparative cross-country models encompassing 19 economies to show that the price of Brent crude oil jumped 55.3% from $72.48 to $112.57 per barrel within one month; the OLS model captures 84.7% of the variance of 19 cross-country GDP revisions (R² = 0.847); and the IMF downwardly revised its forecast of global GDP growth from 3.3% to 3.1% in its best-case scenario, while the worst-case scenario led to recession risk if the conflict continued into 2026. Global inflation forecasts increased 0.6 percentage points to 4.4%, with scenarios of continuing conflict projecting inflationary rates above 6%. The research shows that Iran, Iraq, Kuwait, Qatar, and Bahrain are the worst-affected economies, with evidence of unequal sharing of costs that affect energy-importing emerging markets in Asia and Sub-Saharan Africa. The study addresses a gap in the literature by offering the first holistic quantitative approach to this conflict's economic structure, alongside recommendations for policies to counter this crisis by monetary policymakers, international organisations, and energy security analysts.