This study was conducted to understand pre-service and in-service teachers' intentions to use mobile-based assessment in classes by integrating theory of planned behaviour, technology acceptance model, and self-determination theory into one conceptual framework. Data were analysed using the structural equation model (SEM). Results of SEM from a sample of 522 pre-service teachers and 279 in-service teachers revealed that, compared to existing theories, the proposed model has a better acceptable level of explanatory power for intention to use mobile-based assessment. Results also showed that all the hypothesis relationship among constructs within the model was supported. In addition, the study identified the prominent mediating role of perceived usefulness, perceived ease of use, and attitude and moderating impact of gender on intention to use mobile-based assessment. All in all, the study provides useful implications for policymakers, teacher educators, and school administrators as well as suggestions for future researchers.