Martinez Alier has a Lic. Economics, Universitat de Barcelona (1961), after which he went abroad to escape Francoist Spain, and studied agricultural economics at Oxford University and Stanford. He then received a scholarship to return to Oxford (B.Litt. St Anthony's College, 1967). His PhD was in Economics from the Universitat Autonoma de Barcelona (1976).
He remained as a researcher at St. Anthony's College Oxford into the early 70s (1966–73 and 1984–85), working on land reform, rural unemployment and the capitalist logic of sharecropping in Southern Spain and also conducting research in Cuba (on smallholders in the early years of Castro's Cuba) and in Peru (on the hacienda peasantry). He was visiting professor at the State University of Campinas (Brasil) in 1974, before returning to his home town to join the Department of Economics and Economic History at the Universitat Autònoma de Barcelona in Spain, in 1975. He has also been a visitor at the Free University of Berlin (1980–81), Stanford University and the University of California, Davis, (1988–89), Yale University (1999-2001), and FLACSO Sede-Ecuador (1994–95 and 2007–15).
He directed the CEECEC and EJOLT research projects on ecological economics and political ecology between 2008 and 2015. He is officially retired from AUB, but still professionally active and in 2016, aged in his mid 70s, he received a €2 million Advanced Grant from the European Research Council (ERC) for a further five-year project, A Global Environmental Justice Movement - The EJAtlas (www.ejatlas.org). In particular, he has made a fundamental contribution to establishing ecological economics as a transdisciplinary field of study devoted to regulating economic activity in a way that promotes human well-being, sustainability, and justice. In several books and articles, he has analysed the relationship between ecological economics and political ecology as well as the role played by environmental justice. Most important is his approach to environmental conflicts and the notion of “ecological unequal trade”. Among his numerous important publications, one of the most influential is the volume The Environmentalism of the Poor (Edward Elgar, 2002), based on the author’s experiences researching in India and Latin America.
His interests are agrarian studies, ecological economics and political ecology. In the late seventies Martinez Alier became interested in agricultural energetics and the work of Sergei Podolinsky (1850-1891), publishing a text on this with J.M. Naredo in 1982.
He is a practitioner of ecological economics, defining many of its key concepts approaches. He argues, against neoclassical economists, that the economy is not circular, but entropic. Calculations of social metabolic flows of energy and materials need to figure in neoclassical and marxist economics. Energy is not recycled and materials are only partially recycled - and resource extraction and waste disposal manifest themselves in ecological systems. They are visible through the drawing down of physical resources, pollution, and through socio-ecological distribution conflicts. The latter are hastened by an increase in social metabolism and human appropriation of nature. "In environmental struggles, reproduction of human society and of nature’s functions are more important or just as important as fights over the (purported) economic surplus.".In recognition of his contribution to innovating economics studies, he was awarded the prestigious Leontief Prize for Advancing the Frontiers of Economic Thought in 2017 for his groundbreaking theoretical and applied contribution integrating ecological approaches with developmental and justice-oriented ones. He has been extremely active in the dissemination of research results and in the promotion of environmental justice. The Atlas of Environmental Justice he co-directs is a unique, open-access database on the main ecological conflicts and their cultural expressions, which constitutes a highly useful source for scholars in several disciplines, as well as practitioners in the field. In 2020 he was awarded the Balzan Prize.