Undergraduated in Mathematics at the Federal University of Rio de Janeiro – UFRJ (1967), master degree in Mathematics at the National Institute of Pure and Applied Mathematics – IMPA (1972), PhD in Mathematics at the Catholic University of Rio de Janeiro – PUC-Rio and the National Institute of Pure and Applied Mathematics – IMPA (1981) and Privat Dozen in Mathematical Economics (1999) at the University of São Paulo – USP.

She was Professor at PUC-RJ – Catholique University of Rio de Janeiro (Department of Mathematics), UERJ- State University of Rio de Janeiro (Department of Mathematics), UFRJ –Federal University of Rio de Janeiro (Industrial Economics Institute) and USP/SP – State University of São Paulo (Economics Department).

She was Visiting Researcher at Pittsburgh University (USA), Institut des Hautes Études Scientifiques (France), Universidad Autònoma  de Barcelona (Spain), École Polytechnique (France), University of California at Berkeley (USA) and distinguished visiting professor at Brown University (USA). 

Nowadays, she is Professor at EPGE Brazilian School of Economics and Finance of Getúlio Vargas Foundation - RJ.

She is Fellow of the J. S. Guggenheim Foundation, Fellow of the Econometric Society, Fellow of the Game Theory Society, Economic Theory Fellow and Fellow from the International Core Academy of Sciences and Humanities.

She was elected member of the American Academy of Arts and Sciences in 2020 and of the Brazilian Academy of Sciences in 2015. In 1990, she was elected, for three years, Associate Editor of Econometrica, and in 2003 she was elected Associate Editor of the International Journal of Game Theory, where she served until 2018.

Along her career she received the following awards: TWAS 2016: “For her extraordinary contribution and innovative research in the field of matching markets” (THE WORLD ACADEMY OF SCIENCES FOR THE ADVANCEMENT OF SCIENCE IN DEVELOPING COUNTRIES), Lanchester Prize 1990: “For the outstanding paper in Operation Research” (Operations Research Society of America), Haralambos Simeonides 2001(ANPEC), Mario Henrique Simonsen 2006 (RBE/FGV), Adriano Romariz Duarte 1996 (SBE), Medal of Scientific Merit from the Order of the Brazilian Economists, in 2013, a plaque “by her contribution to the Economic Sciences in the developing of the Matching Theory” awarded by  EPGE FGV in 2014  and a plaque : “in recognition of the academic work of Marilda Sotomayor, from 1997 to 2014”,  awarded by the Department of Economics, USP. In 2015 she was elected “One of the pioneers women in sciences in Brazil” by CNPq- NATIONAL COUNCIL OF RESEARCHES OF BRAZIL.

She is charter member of the Game Theory Society and was elected, twice, as a board member of the Econometric Society. She organized, scientifically, the “First Brazilian Workshop of the Game Theory Society” at USP in 2002,  the “17th International Conference on Game Theory and Economic Applications” at the State University of New York, Stony Brook, in 2006, the “Gale’s Feast: a day in honor of the 85th birthday of David Gale” at the State University of New York, Stony Brook in 2007; the “Second Brazilian Workshop of the Game Theory Society: São Paulo School of Advanced Science in Game Theory of FAPESP,  in 2010, FEA/USP/SP (this workshop honored John Nash and had the participation of the Nobel Prizes in Economics: Aumann, Myerson, Maskin, Paul Milgrom and Nash),  the International Workshop of the Game Theory Society, the second São Paulo School of Advanced Science in Game Theory of FAPESP, in 2014, with the presence of the Nobel Prizes in Economics: Aumann, Maskin, Nash and Roth (this workshop celebrated the 70th birthday of Marilda Sotomayor). She served as Guest Editor of the International Journal of Game Theory for the edition: “A collection of papers dedicated to David Gale on the occasion of his 85th birthday”, published in 2008. She was Editor of the session of Game Theory of the Encyclopedia of Complexity and Systems Sciences, collection of 18 volumes published by Springer in 2010 and one of the three editors of the volume “Complex Social and Behavioral Systems: Game Theory and Agent-Based Models,” at the Encyclopedia of Complexity and Systems Science (2nd Edition), published in 2020. She was member of the Program Committee of  the World Congress of the Econometric Society in 1990 (Barcelona) and in 2000 (Seatle); 3rd World Congress on Game Theory in 2008, in Northwestern University, 4th World Congress on Game Theory, Istambul, 2012 and in several Latin American Meetings of the Econ. Society.

She has written several papers and the book “Two-sided Matching. A study in game-theoretic modeling and analysis”, with Alvin Roth, first publication in 1990. This book received the Lanchester Prize of 1990, awarded by the Operations Research Society of America. In 2010, it was organized the congress "Roth and Sotomayor: Twenty years after” at Duke University, North Caroline, to celebrate de 20 years of publication of the book. 

Her main interest is in the theory of matching markets and its applications to the Economic Theory.