This book offers a comprehensive and interdisciplinary examination of how complexity emerges, transforms, and accelerates across the entire 13.8-billion-year history of the Universe. It brings together chapters from leading researchers to explore the deep structure of complexity—from cosmic origins and planetary evolution to biological innovation, human development, civilizational dynamics, and possible future trajectories. Notably, several chapters bridge multiple phases of Big History, providing valuable cross-disciplinary insights—such as comparisons between cosmic and terrestrial evolution and analyses of energy dissipation across physical and complex adaptive systems. This book offers a comprehensive exploration of complexity’s manifestations and transformations across time and scale. By exploring these diverse topics, the book contributes to the broader field of Big History, deepening our understanding of complexity’s interconnected nature across the cosmos, life, and human civilization.