She has served as an associate professor of chemistry at Fort Valley State University, an associate professor of environmental science, an assistant vice provost at the University of Texas at Arlington, and executive director of the Institute for Broadening Participation. She also held faculty positions at the Georgia Institute of Technology School of Earth and Atmospheric Sciences, the Savannah State University Marine Science Program, the University of South Florida College of Marine Science, the University of Texas at Arlington Department of Earth and Environmental Sciences, and the Mercer University Department of Education. Currently, Johnson is a professional speaker on topics of diversity and inclusion in higher education, Youth STEM advocacy, and workplace equity.