Mobile edge computing (MEC) is emerging as a new paradigm that combines mobile networks and edge computing, which has popularized in academia and industry in recent years. MEC provides mobile end users with low latency in their access to applications deployed at the edge of the network. Many artificial intelligence (AI) applications such as smart assistant, driverless cars, and smart city powered by machine learning demand low latency services. MEC combined with AI makes it possible for unlimited usage in people's daily lives.In MEC environment, computing resources are provisioned and managed on edge servers that are geographically distributed. Accordingly, AI applications in the MEC environment are deployed in a highly distributed manner. However, different from centralized cloud computing environment, security techniques and mechanisms should be designed to protect the server, application, and devices operating in the mobile edge environment. In addition, the virtually unlimited computing capabilities offered by the cloud are not available for edge servers and applications on edge servers to fight cybersecurity attacks because of their limited physical size and high geographic distribution. Therefore, the unique features of MEC raise many opportunities as well as privacy and security challenges to AI applications, for example, data privacy attacks, adversarial attacks, and confidentiality attacks. Currently, the lack of techniques, mechanisms, and tools specifically tailored to ensure security has become the main obstacle to broader and further applications of AI in MEC environment.Keeping this in mind, this special issue addressed significant challenges in solving new security-related issues that challenge AI applications in MEC environment and attracted cutting-edge outcomes of secure AI from a wide range of perspectives including architecture, software, algorithm, etc. We have received 69 submissions in this issue, and we accepted 11 high-quality submissions for publication (acceptance rate is 15.9%) after a rigorous review process with at least three reviewers for each paper. The authors are from diverse countries and regions, including