Numerous efforts have been mooted in the attempt to exploit the potential in mHealth towards addressing and tackling the growing global disease burden. A survey of literature indicates that a significant number of mHealth projects in developing countries fail the sustainability test, a measure that evaluates the ability of a solution to continuously meet the primary objective. This study sought to develop a model for evaluating the sustainability of mHealth systems. By adopting the exploratory research design; proposed parameters for evaluating sustainability of mHealth system are identified through review of various categories of literatures: evaluation models, mHealth sustainability evaluation models, mHealth experiences in developing countries. Using these factors, a conceptual model is formulated and statistically validated using Partial Least Squares, a component of Structural Equation Modeling (PLS-SEM) found in the SmartPLS software. The outcome of the study revealed that sustainability of mHealth systems in developing countries is influenced by nine factors; Management Factors - Ownership, Technological Factors – System Quality, System Interoperability, Technology Sustainability, System Relevance, System Scalability and Individual Factors – User Support, System Access and User satisfaction. The nine factors explained 58.2% of the variance in the sustainability of mHealth system. Ownership, User support, Technology Sustainability and User Satisfaction had the stronger influence on Sustainability of mHealth. The factors explained 13.25%, 11.09%, 8.7% and 7.01% of the variance respectively. Management factor (ownership) was found to have the greatest influence on sustainability of mHealth in developing countries. An evaluation score matrix is also proposed.