Mark Garrett holds a Ph.D. in urban planning from the University of California, Los Angeles (UCLA) Luskin School of Public Affairs and a J.D. from the UCLA School of Law. For a number of years he was a practicing attorney in California specializing in land use, transportation, and environmental issues. He is currently serving as a member of the research faculty in the Lewis Center for Regional Policy Studies at UCLA and also teaches courses in the Department of Urban Planning. Garrett is the co-author with Martin Wachs of Transportation Planning on Trial: The Clean Air Act and Travel Forecasting, and has contributed to articles in the UCLA Journal of Environmental Law and Policy, the UCLA journal Critical Planning, the Berkeley Planning Journal, the Transportation Research Record, and the Journal of the American Planning Association.

Garrett has been an adjunct professor in the Saint Louis University (SLU) School of Law and a faculty member in the Department of Policy Studies in SLU's College of Education and Public Policy. He has also taught at the Ohio State University, the University of Michigan, the University of Illinois, and Virginia Commonwealth University.

His current research focuses on sustainability and legal and social equity aspects of urban land use and transportation planning. He presently resides in Los Angeles, California.