She moved to the University of Michigan for graduate study, beginning with a master's degree in marine engineering but then shifting to electrical engineering and computer science,[6] as she became more interested in automotive applications of control theory.
[7] In 2000 she returned to the University of Michigan as an associate professor of mechanical engineering,[6] and began the work on fuel cells for which she is best known.
[2] Stefanopoulou is the co-author, with Jay T. Pukrushpan and Huei Peng, of the book Control of Fuel Cell Power Systems: Principles, Modeling, Analysis and Feedback Design (Springer, 2004).
[8] Stefanopoulou was named a fellow of the American Society of Mechanical Engineers in 2007.
[11] The University of Michigan named Stefanopoulou to the William Clay Ford Professorship in 2017.