This book constitutes the proceedings of the 12th Annual International Conference on Information Management and Big Data, SIMBig 2025, held in Lima, Peru, during October 29–31, 2025.The 36 full papers and 1 short paper included in this book were carefully reviewed and selected from 101 submissions. SIMBig 2025 introduced innovative approaches for analyzing and handling datasets as well as new methods based on Artificial Intelligence (AI), Data Science, Machine Learning, Natural Language Processing, Semantic Web, Data-driven Software Engineering, Health Informatics, and more.