This book features carefully selected research papers presented during the 9th International Conference on Discrete Mathematics and Mathematical Modelling in the Digital Era (ICDMMMDE-2023). The conference, organised at the Department of Mathematics, The Gandhigram Rural Institute in Gandhigram, Tamil Nadu, India, took place from 23–25 March 2023. Serving as a dynamic platform, the event attracted emerging researchers, mathematicians, industrialists, scientists, and engineers from across the globe, fostering discussions on pertinent research topics. This volume showcases noteworthy contributions from esteemed researchers within the realm of discrete mathematics and mathematical modeling, meticulously subjected to a rigorous peer-review process for publication. The included papers delve into diverse subjects, including controllability, image processing, topology, graph theory, fuzzy delay differential equations, analysis, queuing theory, and applications in networks and biology. Theculmination of these contributions forms a comprehensive and authoritative resource for scholars and professionals alike.