Leyens completed his PhD at Universität Hamburg in 2006 with a dissertation on company law. He went on to complete his habilitation phase there in 2015 with a publication on capital markets law. Prof. Dr. Dr. Dr. h.c. mult. Klaus J. Hopt, M.C.J. (NYU) supervised both publications. Leyens was a research assistant and later senior research fellow at the Max Planck Institute for Comparative and International Private Law in Hamburg between 2001 and 2007. In 2007, he was then appointed Junior Professor of Private Law and Economic Analysis of the Law at Universität Hamburg. Since 2014, he has held the role of honorary Professor of Law & Economics at Erasmus University Rotterdam. He held the Professorship for Law & Business at the University of Graz until joining the University of Bremen.