In 1988–1991, Mtingwa worked at Argonne National Laboratory, where he developed theory of advanced wakefield and plasma acceleration and of the photon colliders. Starting in 1991, he joined the faculty at North Carolina A&T State University as Chair and Professors of Physics (with a brief stint at Morgan State University in 1997–1999). From 2001 to 2003, he was a visiting professor of physics at MIT, followed by two years as a visiting professor of physics at Harvard University. He returned to MIT in 2006. He retired in 2012 and has since focused on outreach efforts.