This book collects peer-reviewed and presented papers from 2025 9th International Conference on Natural Language Processing and Information Retrieval (NLPIR 2025), held in Kyushu University, Fukuoka, Japan during December 14–16, 2025. Nowadays, advances in computer engineering made it possible that humans may interact with the machines in their natural language either in the written or the spoken manner. At the same time, the amount of (textual) data available in big data bases as well as the World Wide Web is growing in a rapid manner. Both developments setup new challenges for the development of innovative algorithms to recognise speech, to categorise and classify not only textual information in short times as well as to extract knowledge and wisdom from a huge pile of raw, unevaluated data.  Topics discussed in this book include Syntactic Analysis, Language Representation and Machine Translation, Multimodal NLP Recognition, Semantic Analysis and Modelling, Sentiment Analysis and Corpus Construction, Generative Text and Text Classification, Speech Recognition Models and Detection Techniques, Context-Aware Large Language Models and Parameter Adaptation, Language Representation and Information Retrieval in Multimodal Information Systems, AI-Based Generative Dialogue Systems and Intelligent Question Answering Systems, Text Mining and Knowledge Extraction Based on Generative Frameworks, Mechanisms and Applications of Artificial Intelligence in Natural Language Tasks, Cross-Document Information Extraction and Information Detection Based on Pre-trained Language Models.