Mythili earned her B.Sc.Eng. (Hons.) degree in Civil Engineering from the University of Peradeniya, Sri Lanka in 2008, and M.S. degree in Civil Engineering from the University of Houston in 2017. She joined the Grainger Institute for Engineering in August 2017. Prior to that, she worked as a Research Assistant at the California Institute of Technology, and at the Swiss Federal Institute of Technology (ETH Zurich), Switzerland. Before moving to USA, she was a Project Engineer at the Mahaweli Authority of Sri Lanka, which is responsible for major dams and reservoirs in Sri Lanka.