Engaging in clinical trials in Africa not only enhances researchers' comprehension of local health concerns but also plays a crucial role in tackling global health challenges. In Tanzania, there has been a surge of clinical research for the past 10 years indicating a need to improve ethical and clinical trial regulatory capacity. Several initiatives to address the clinical trial regulatory and ethics challenges have been done. Lessons from such initiatives are important to inform evidence-based decision-making for sustainability. The ASCEND project with the theme of “Moving Tanzania’s Clinical Research Ethics and Medicines Regulatory Capacity to the Next Level: Fostering Medicine Quality, Safety and Good Clinical Practice (GCP) on Clinical Trials” was implemented in Tanzania Mainland and Zanzibar from November 2020 to December 2023. A thorough review of the project implementation reports and on deliverables was conducted to identify the lessons learned. Inductive content analysis was used to analyze the information. A total of seven lessons were deduced from the reviewed documents. These include capacity building through training on clinical trials review and approval process, research ethics and GCP inspection which cannot be overlooked; engaging the community in reporting adverse drug events is worth considering; digitalization of electronic systems enhances clinical trial control and creates a dynamic regulatory ecosystem; compliance to requirements for clinical trials conduct is enhanced by training of early and mid-career researchers; networking and broad stakeholders’ engagement and participation in ethics and regulations governing clinical trials is a cornerstone for strengthening collaboration between researchers and regulators; the need for electronic systems for monitoring and evaluation of the project is inevitable and the need for adhering to project timelines is crucial for successful implementation of the project. Sustainability is the take-home message from the ASCEND project and should inform stakeholders for future improvement. Continuous investment and advancement in research ethics and regulatory oversight across Africa should be prioritized.