Computational simulation has become a fundamental pillar of the scientific method. Among other factors, the advances in computational resources in both hardware and software, have accelerated the adoption of computational methods to formulate models, establish hypotheses, and generate experimentally verifiable predictions. In particular, complex systems that comprise large numbers of interacting elements are well-suited for computational approaches due to their often counterintuitive behaviour and the existence of large amounts of data from different modalities. Among other techniques, agent-based simulation (ABS) has gained significant attention in recent years. In addition to ABS, this workshop will focus on research based on different computational approaches to better understand complex systems across a broad range of domains, including, for instance, neuroscience, oncology, and other complex biological systems. The COMBYNE lab (COmputational Modelling of Biologial dYnamics and EngiNEering) at the University of Surrey is delighted to host the “Computational Modelling of Complex Biological Systems 2023” (CMCBS23) workshop. CMCBS23 takes place on June 23rd at the University of Surrey (Guildford).