An Artificial Pancreas (AP) system centered around an Android Smartphone is proposed in this paper. This unique architecture involves two separate but interacting modular Android applications (Apps) that are designed for unique functionalities. Even though an artificial pancreas system is a safety-critical system that demands a complex architecture and careful coding process, owing to their modular nature, these apps could be designed and developed through rapid prototyping processes. The first app (App-A), which runs in the front-end, serves as the user interface and acts as a connection hub for the hardware devices, was developed on the Android studio platform. Necessary communication protocols to enable communication with the hardware devices are incorporated into this app. The second app (App-B), which runs in the back-end, is developed using Simulink’s Android support package. It contains a safety-critical model predictive control algorithm with appropriate constraints to compute the required insulin rate, augmented with a Kalman Filter for estimating the states. There is an additional safety logic as well to prevent insulin over-dosage, thereby augmenting to the cause of a safety-critical control algorithm. The contribution of this work is a modular software framework and prototyping methodology that can be used for rapid development, testing and deployment of Android based AP-systems.