Professor Kimberly Thomas's research, teaching, and practice concentrate on criminal law and procedure, especially on sentencing law and practice, juvenile justice, parole and post-conviction, and indigent persons accused of crimes. Professor Thomas is the cofounder (with Professor Frank Vandervort) of the Juvenile Justice Clinic.

In 2017, Professor Thomas received a Fulbright Scholar award to teach and research juvenile justice at the School of Law at University College Cork in Cork, Ireland. In 2013, Professor Thomas was among several attorneys honored with the Justice For All Award from the Criminal Defense Attorneys of Michigan for their training and pro bono support following the 2012 U.S. Supreme Court Miller v. Alabama decision holding that mandatory juvenile life-without-parole sentences were unconstitutional. Professor Thomas also has been engaged as a legal education expert for the American Bar Association Rule of Law Initiative in Jordan, Egypt, and Turkey, including in 2011, when Professor Thomas spent three months in Amman, Jordan, working on law school curriculum development, especially in criminal law, as well as the creation and support of experiential education and the first clinics in the country.

Prior to joining the Law School faculty in 2003, Professor Thomas served as a major trials attorney with Defender Association of Philadelphia.