With the recent increase of infectious diseases characterized by epidemic outbreaks whose origin are from environmental factors, the use of environmental variables such as water bodies and weather variables for effective diseases analysis has dramatically increased. The situation has stirred up efforts of software engineers towards integrating the collection of environmental factors from Environmental Management Systems (EMSs) into Healthcare Information Systems (HISs). HISs and EMSs have a large diversity of stakeholders and technological application domains; as a result, they face interoperability complexities. In spite of the established knowledge of software-architecture, there is still a lack of unified architecture for integrated Healthcare and Environmental Management Information Systems (HEMISs) to support the development of HEMISs and solve the interoperability challenge in a holistic way. This work proposes conceptual design view of the unified architectural model for HEMIS that would serve as a blueprint for the development of HEMISs and also, enhancing the analysis of epidemic diseases which have a strong linkage with environmental factors. As a proof of concept, the designed unified architecture has adopted features from IEEE 42010-standard, Siemens’ Four View Model, Protocol Translator and Key Attribute Value table architecture style, and used Unified Modeling Language (UML) in its design visualization.