This paper investigates efficiency and freedom as joint foundations of market economies. Whereas ideal perfect competition accommodates Mill’s principle of individual liberty in the economic arena, in real world, imperfectly competitive, markets economic freedom and efficiency appear often as conflicting values. Building on J. S. Mill’s utilitarian defense of free trade in On Liberty Chapter V, this paper puts forward a consequentialist defense of economic freedom under imperfect competition. Defense rests on the instrumental value of equal freedom, enjoyed by every market agent, as a source of general welfare in a world of dispersed information among unique human beings. The paper has a clear impact on contemporary antitrust debate, supporting neo-Brandesians’ rehabilitation of Structuralism in antitrust also on well founded, economic, i.e. efficiency, reasons. © 2023, The Author(s).