This chapter starts by exploring microservices and architecting them using GKE and Anthos. GKE notably provides a managed Kubernetes environment, which simplifies container orchestration. Anthos leads to extended use of the microservices on both hybrid and multi-cloud settings. The two services make managing microservices on GCP easier. The chapter then looks at fine-grained access control using Kubernetes RBAC (role-based access control). This chapter covers the model for designing and enforcing RBAC policies that will enhance authorization and access for the resources in Kubernetes clusters. The chapter then looks at communication security using mTLS and Istio Service Mesh. Using mTLS enables communication between microservices to be authenticated and encrypted, leading to secure communication. Istio is a simpler use of mTLS, ensuring traffic management, policy enforcement, and observability. The chapter explains the steps for configuring Istio on GKE to enable secure communications. At the end of this chapter, you will have a comprehensive understanding of designing, implementing, and using critical security for microservices on GCP. A secure architecture means that scalable microservices with high security standards can be used on GCP to enhance everyday needs.