Access to traditional education is expensive and has limitations related to geographical locations. The internet development has enabled the use of alternative tools for providing teaching and learning services referred to as Massive Open Online Courses (MOOCs). Despite the advantages of using MOOCs in Higher Learning Institutions (HLIs), there is a paucity of studies related to the adoption of MOOCs in developing countries. Furthermore, the self-regulation aspect, an important factor in an uncontrolled learning environment has received less attention in the literature. Nevertheless, available studies on the adoption of MOOCs have not paid attention to the issue of the age difference, which is important in adopting innovative technology. Therefore, to address the gap this study extended the Technology-User-Environment (TUE) framework by examining mediating and moderating effects of self-regulation and age respectively on the adoption of the MOOCs in Tanzania. The study employed purposive sampling to collect a total of 351 which were analyzed using SmartPLS 4.0. Findings show that observability, perceived usefulness, peer pressure, self-regulation and self-efficacy have significant effects on the adoption of MOOCs. Furthermore, findings show that age moderates the relationship between peer pressure and MOOCs adoption behaviour. Also, Self-regulation was found to mediate the relationship between perceived usefulness, personal readiness, observability and MOOCs adoption. The study provides recommendations to enhance the adoption of MOOCs in Tanzania's higher education sector.