During school, Dr. Dorsey served as a U.S. State Department Delegate at the UNCED Earth Summit (1991-1992), a Researcher at the African Centre on Technology Studies (1993-1994), and a Visiting Scholar/Consultant at the World Resources Institute (WRI). In the latter role, he lectured on results from the Earth Summit and assisted with the African Future Scenarios 2050 Project. After earning his degree, he lectured at Kungl Tekniska Hogskolan (Royal Institute of Technology) (2001), the University of Witwatersrand Graduate School of Public & Development Management (2002), and Dartmouth University (2003-2005). Dr. Dorsey was appointed Director of the Sierra Club, first serving from 1997-2003 before later appointments in 2014-2017 and 2022-2025. In 1999, he Founded and Directed the Environmental Leadership Program (ELP), where he helped advance leadership in the environmental field through programming and identifying funds to support new and emerging environmental leaders.

From 2005-2012, Dr. Dorsey worked as an Assistant Professor at Dartmouth College, researching social and climate justice. He was then selected as a Visiting Fellow and Professor in the College of the Environment at Wesleyan University (2012-2013) and a Visiting Scholar at the Joint Center for Political and Economic Studies (2009-2016). Dr. Dorsey continued with the Joint Center for Political and Economic Studies as the Interim Program Director of the Energy and Environment Program (2013-2016). Highlighting his influential leadership and extensive energy and environmental knowledge, Dr. Dorsey served as the Senior Program Officer at the National Academy of Sciences from 2016-2018.

Dr. Dorsey co-founded DetroitxPAC and the Center for Environmental Health in 2013 and 1996, respectively. In the latter role, where he also served as Director for almost 27 years, he advanced research to reduce environmental health hazards and oversaw several staff members. In 2017, Dr. Dorsey co-founded the Sunrise Movement, a nationwide movement focused on climate change and climate action. He served as Treasurer until 2022. Dr. Dorsey currently serves in several capacities related to energy, equity, and the environment, including as Director & Equity Partner at Univergy Solar/ThinkGreen (2017-present), Director of the Michigan Environmental Council (2019-present), and Director & Chair of the Rob and Melani Walton Sustainability Solutions Service at Arizona State University, with a joint appointment as a Professor of Practice in the College of Global Futures. At ASU, he leads a team that advances sustainability solutions related to energy, finance, and justice.

Dr. Dorsey was formerly a member of the NAACP (2000-2009), an Advisor for the Center for Genetics and Society (2000-2012), and a Board Member at CorpWatch (2000-2012). He is currently a Member of Progress with Friends and the Club of Rome, an Advisor for ImpactPPA, and a Partner with Univergy Solar and Pahal Solar. Additionally, he serves as the Secretary of Black Owners of Solar Services. His work has also appeared in the Los Angeles Times and The Wall Street Journal, among others. Dr. Dorsey was also appointed as an environmental advisor on the 2008 Obama Presidential Campaign while teaching at Dartmouth. He has received awards for his work, including Rotary International's Paul Harris Medal for Distinguished Service to Humanity in 1997 and a nomination for the Ford Foundation's Leadership for a Changing World Award in 2000.