Following his PhD, Rajan joined the Department of Computer Science faculty at
Iowa State University as an
assistant professor in 2005. He rose through the academic ranks, becoming
associate professor in 2011 and
full professor in 2016. His early work, focused on programming languages and software design, developed language features to enable improved modularity for complex software systems to reduce defects and to improve software quality. He also focused on language features for improving concurrent programming. For this research, he was named an
ACM Distinguished Member. His later works have focused on programming languages and data science infrastructure for analyzing large-scale datasets. During the
COVID-19 pandemic, Rajan co-developed a data science infrastructure to improve research efficiencies for scientists who study the novel coronavirus. The tool enables scientists to quickly and efficiently locate, navigate and analyze coronavirus research from all over the world. He helped develop and establish the
National Science Foundation Dependable Data-Driven Discovery Institute at Iowa State University. For this work, he was awarded a 2018-19 Fulbright U.S. Scholar Award from the J. William Fulbright Foreign Scholarship Board. He was also appointed the Kingland Professor of Data Analytics. His subsequent works have focused on improving
deep learning, for which he has received a
Facebook Probability and Programming Award, and an ACM SIGSOFT Distinguished Paper award. He was also elected a fellow of the
American Association for the Advancement of Science for "distinguished contributions to data driven science, particularly to modularity and modular reasoning in computer software and the development of the Boa language and infrastructure." Rajan served as the chair of the Iowa State University Department of Computer Science from 2019 to 2024. In 2024, he was appointed the Dean of the
School of Science and Engineering at
Tulane University. ==Awards==