Leiss started his academic career in the political science department at the University of Regina, before moving on in 1973 to two stints with the Faculty of Environmental Studies at York University (also political science and the graduate programme in social and political thought there), interrupted by a brief stay at the University of Toronto's Department of Sociology; then in 1980 to the School of Communication at Simon Fraser University, where he was department chair for six years and later Vice-President, Research. He was awarded the five-year, externally funded Eco-Research Chair in Environmental Policy at the School of Policy Studies, Queen's University, in 1994 and was then in the Faculty of Management at the University of Calgary where he held a five-year research chair, the NSERC/SSHRC/Industry Chair in Risk Communication and Public Policy, funded under the granting councils' Management of Technological Change program. He is now at the University of Ottawa, in the R. Samuel McLaughlin Centre for Population Health Risk Assessment as Scientist and Adjunct Professor.
His work on risk communication in science and policy has informed recent analysis on biotechnology governance in Canada by political scientists G. Bruce Doern and Michael J. Prince.