This book constitutes extended, revised and selected papers from the 9^th 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.