IoTaaS is endorsed by the European Alliance for Innovation, a leading community-based organization devoted to the advancement of innovation in the field of ICT. The 4th International Conference on IoT as a Service (IoTaaS) aims to contribute to the discussion on the challenges posed by Internet of Things (IoT). The IoTaaS conference aims to bring together researchers and practitioners interested in IoT from academia and industry. IoTaaS attendees will present novel ideas, exchange points of view, and foster collaborations. In 2018, the city of Xi’an, a famous historical and cultural city of China, will host IoTaaS 2018. The conference will consist of technical symposia, tutorials, posters, demos, and workshops. All submissions to this conference will be subject to rigorous peer review before included in the technical sessions.