As reflected in the title, the main objective of the paper is to explore an appropriate approach to promote technological innovation for developing countries. Aiming to this goal, the paper studies three main innovation system approaches, whose implantation is being attempted in developing countries: first, national innovation systems (NIS), which was developed in OECD countries; second, the system of innovation for development (SID), which is a concept that tries to adapt NIS to developing countries; and third, inclusive innovation which is a pro-poor innovation system. Based on the strengths and the weaknesses of each concept and their potential adaptation in developing countries, the paper proposes an integrated approach of innovation system for developing countries. Compared to developed countries, the concept of innovation system in developing countries should be more complex because it involves not only the formal sector such as enterprises, universities, research institutes, government, and financial system but it also involves NGOs, informal companies, grassroots inventors, local and indigenous knowledge, etc. The last part of the paper discusses the ideas that innovation stakeholders in developing countries can use to promote their proper innovation system.