Thomas C. Mettenleiter studied biology from 1977 to 1982 and earned his doctoral degree in genetics in 1985 at the Eberhard Karl University of Tübingen for his research work on pseudorabies virus conducted at the Federal Research Centre for Virus Diseases of Animals (BFAV) in Tübingen. With a research fellowship granted by the German Research Foundation (DFG) he went for a research stay with Tamar Ben-Porat and Albert Kaplan at Vanderbilt University, Nashville, TN, USA, from 1986 to 1987. After returning to BFAV, he obtained his post-doctoral habilitation in virology at the University of Tübingen in 1990. 

From 1994 to 2019 he chaired the Institute of Molecular Virology and Cell Biology at the Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health (FLI), on the island of Riems. He has been leading the FLI since 1996, in 1997 he was appointed President of the FLI. His main field of research is virus infections of farm animals, in particular herpesviruses. In addition to studies on the basic processes of virus-host interactions, he is involved in the development of novel vaccines based on molecular biological techniques. He is a member of several international committees and working groups including the founding co-chair of the „One Health High Level Expert Panel” jointly initiated by WHO, OIE, FAO, and UNEP. 

He is a member of the German National Academy of Sciences Leopoldina, the Academy of Sciences in Hamburg, the Polish Academy of Sciences, and the Royal Belgian Academy of Medicine. He has been awarded honorary doctorates from the University of Veterinary Medicine Hannover and from the Justus-Liebig-University Gießen, an associate professorship from the University of Greifswald and an honorary professorship from the University of Rostock. He is also a recipient of the Robert von Ostertag Medal of the German Federal Chamber of Veterinarians. He is senior editor of the scientific journal „Advances in Virus Research“.