In today's world, Sustainable development is becoming a crucial part to meet the increasing demand of future generations. The 6th International Conference on Intelligent Sustainable Systems [ICISS 2023] is one of the initiatives toward attaining sustainable development and facilitating collaborative forums in international level. It provides unique opportunity to bring together academicians, researchers, scientists and research scholars to share and exchange ideas and practical solutions towards achievement of intelligent sustainable systems for a more sustainable future. This conference also aims to create an interdisciplinary platform to share their research ideas on developing new models and algorithms for sustainable development and provide intelligent paradigm shifts to deal with uncertainties and imprecise problems in real-world. ICISS 2023 is an annual international conference that aims to enhance the intersection of intelligent systems and sustainability. The Conference mainly aims to explore and share cutting-edge research knowledge for future sustainable collaboration. The research works that discusses the tools, methodologies, practices, and applications of sustainable systems and computational intelligence methodologies.