This book constitutes extended, revised and selected papers from the 9th International Conference on Cloud Computing and Services Science, CLOSER 2019, held in Heraklion, Greece, in May 2019.The 11 papers presented in this volume were carefully reviewed and selected from a total of 102 submissions. CLOSER 2019 focuses on the emerging area of Cloud Computing, inspired by some latest advances that concern the infrastructure, operations, and available servicesthrough the global network.