This book constitutes the refereed proceedings of the 32nd International Symposium on String Processing and Information Retrieval, SPIRE 2025, held in London, UK, during September 8-11, 2025.The 17 full papers and 6 short papers included in this book were carefully reviewed and selected from 42 submissions. These papers cover research in all aspects of string processing, information retrieval, computational biology, and related applications.