Formerly, he worked as an architect at the professional offices of Frank Gehry in Los Angeles, Moshe Safdie in Massachusetts, and I.M. Pei in New York. He has won many awards including: Fulbright Scholarship, LafargeHolcim Acknowledgement Prize, Ove Arup Foundation Grant, Architect R+D Award, AIA New York Urban Design Merit Award, Victor Papanek Social Design Award, 1st Place International Architecture Award, Zumtobel Award for Sustainability, Architizer A+ Award, History Channel Infiniti Award for City of the Future, and Time Magazine Best Invention with MIT Smart Cities. He is a TED Senior Fellow and has been awarded fellowships with Safdie Architects, and the Martin Society for Sustainability at MIT.

Mitchell was featured in numerous articles: “The 100 People Who Are Changing America” in Rolling Stone, “The Smart List: 15 People the Next President Should Listen To” in Wired, “50 Under 50 Innovators of the 21st Century” by Images Publishing Group, “The NOW 99” in Dwell, and “Future of The Environment” in Popular Science. He co-authored four books, “Super Cells: Building with Biology” (TED Books), “Global Design: Elsewhere Envisioned” (Prestel, 2014), “XXL-XS: New Directions in Ecological Design” (Actar 2016), and “Design with Life: Biotech Architecture and Resilient Cities” (Actar 2019).

His design work has been exhibited in numerous locations including MoMA in New York, DOX Center for Contemporary Art in Prague, MASS MoCA in North Adams, The Building Centre in London, DAZ in Berlin, OCAD in Toronto, NAI in Rotterdam, Seoul Biennale, and Venice Biennale. Previously, he was the Frank Gehry Chair at the University of Toronto and faculty at Pratt, Columbia, Syracuse, Rensselaer, Washington (St. Louis), Cornell, Parsons, and EGS. He earned a Ph.D. at the Massachusetts Institute of Technology, MAUD at Harvard University, M.Arch at Columbia University with honors.