In 1999 he joined the Computer Science Department at Brown University as an Assistant Professor and was promoted to Associate Professor in 2004. Between 2004 and 2006, he came back to Europe where he became the Director of the Fraunhofer Institute for Integrated Publication and Information Systems IPSI, while he held a position as a Professor of Computer Science / Chair of Intelligent Systems at the Technical University of Darmstadt. He is also co-founder and former Chief Scientist of Recommind Inc, a privately owned company focusing on intelligent enterprise search technologies. Since July 2006, Thomas Hofmann was a Director of Engineering at Google and of one the site leads of Google’s engineering center in Zurich, Switzerland.

Prof. Hofmann's research focuses on machine learning, applications and methods for information and knowledge management, development of intelligent surch machines, automatic annotation, categorization and extraction of information, personalized information filters and product recommendation systems.