Rajan joined the Department of Physiology at Monash University in 1987 as a research fellow, becoming a lecturer in 1995. He served as the Director of Education for the School of Biomedical Sciences from 2013 to 2016. He has received numerous teaching awards and popular student recognition for his efforts in education and has been a proponent of digital technologies in higher education. He is a board member of the Australian Data Science Education Institute. Since 2017, he has served as the national coordinator of the Australian competition of the International Brain Bee for high school students. Rajan serves on the advisory boards of the Eisdell Moore Centre and Redenlab.