This conference proceedings LNCS 12782 constitutes the refereed proceedings of the 9 th International Conference on Distributed, Ambient and Pervasive Interactions, DAPI 2021, held as part of the 23 International Conference, HCI International 2021, which took place in July 2021. The conference was held virtually due to the COVID-19 pandemic. The total of 1276 papers and 241 posters included in the 39 HCII 2021 proceedings volumes was carefully reviewed and selected from 5222 submissions. The papers of DAPI 2021, Distributed, Ambient and Pervasive Interactions, are organized in topical sections named: Smart Cities; IoT, Sensors and Smart Environments; Learning and Culture in Intelligent Environments; Designing Intelligent Environments.