This volume constitutes the refereed proceedings of 9th International Workshop on Annotation of Real-World Data for Artificial Intelligence Systems, ARDUOUS 2025, held in Bologna, Italy, during October 25-26, 2025.

The 11 full papers included in this book were carefully reviewed and selected from 16 submissions. These papers have been categorized into the following themes: Automating Ergonomics: Scalable AI for Technical Hand Grip Classification; Activity Recognition; Annotation of Textual Data; Relation Extraction from Real-World Unstructured Text in the Domain of Dementia.